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Thursday, October 17, 2019

Optimal Page Replacement Policy in Operating System - CodeTextPro

Optimal page replacement policy in an operating system with an example:
Replace the page that will not be used for the longest period of time.
Don’t replace that page which will be used in the near future.

In this post, we will learn how the optimal page replacement policy work.
In an operating system, whenever a new page is referred and not present in memory, a page fault occurs and the Operating System replaces one of the existing pages with the newly needed page. Different page replacement algorithms suggest different ways to decide which page to replace. The target for all algorithms is to reduce the number of page faults. In this algorithm, OS replaces the page that will not be used for the longest period of time in the future.

Optimal page replacement Example-1.
Page reference string: 7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3, 2, 1, 2, 0, 1, 7, 0, 1
Frame size=3

Optimal page replacement Example-2:
Page string: 0, 1, 7, 2, 3, 2, 7, 1, 0, 3

In case of 1:
when insert1, check the previous frame and the existing elements are 2, 3, 7

We see that among three elements (2, 3, and 7) 3 will be used near future.

2 and 7 both are not present in the future.

So here we apply FIFO to break the tie.

Here replace 7 because 7 inserted into the frame before 2.

In case of 0:
when insert0, check the previous frame and existing elements are 2, 3, 1.

We see that among three elements (2, 3, 1) 3 will be used near future.

2 and 1 both are not present in the future.

So apply FIFO to break the tie.

1 will be replaced because between 2 and 1, 1 is inserted before 2.

Optimal page replacement Example-3:

Page reference string: 7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3

Locality of Reference in OS - CodeTextPro

Hanif Miah 1:49 PM 0

Operating System

Locality of Reference in OS - CodeTextPro

Concept of the locality of reference:
Locality of Reference in OS, Concept of locality of reference in Operating System.

In computer science, locality of reference, also called the principle of locality, is the term applied to situations where the same value or related storage locations are frequently accessed. Suppose a programmer began writing programs using block structures. The following constructs are blocked.

1. Compound statements
2. Loops
3. Functions
4. Files.

If a block is a loop consisting of N statements, and if the loop executes 100 times, then for the next 100N instructions the control will remain within the loop.

The mechanism of keeping the program control confined to a block for the maximum time is called locality of reference. In this strategy, the program’s address space is divided into small blocks and each block is stored in contiguous pages.

The advantage of this style of programming is that references become near and remain within a small block on a page.

Thrashing:
The page fault frequency of a process depends upon whether the program was written using the principle of locality of reference. If the programmer has not followed the principle, then a very large number of page faults occur, and the phenomenon is called Thrashing.

Causes of thrashing:

1. Unstructured program:
In an unstructured program, the flow of control does not follow a well-structured path. The address references of operands are made to distant location situations in page s currently not available in the working set of processes. The ‘jump’ statements take control all over, within the variety of the program. So the no of page faults increased.

2. Over committed memory:
If CPU utilization becomes low, then the degree of
multiprogramming is increased by swapping in processes from secondary memory. In this situation, too many processes are squeezed into little memory. If a large no of processes is present in the main memory, then it is difficult for the operating system to provide an adequate number of pages to the processes. And the CPU utilization falls further. If the memory is over committed to a large number of users, then systemic failure takes place.

Segmentation

Segmentation is a memory management technique in which each job is divided into several segments of different sizes, one for each module that contains pieces that perform related functions. Each segment is actually a different logical address space of the program.

When a process is to be executed, its corresponding segmentation is loaded into non-contiguous memory through every segment is loaded into a contiguous block of available memory.

Comparison Chart:

Memory management functions:

Memory management concerned with the following functions. These are
1. Keeping track of memory
2. Determining factor on memory policy
3. Allocation and de-allocation of memory.

Requirements of Memory Management (MMR) - CodeTextPro

Hanif Miah 12:39 PM 0

Operating System

Requirements of Memory Management (MMR) - CodeTextPro

In this post, we will learn about memory management, what is memory management, memory management requirements in os, memory manager, memory management hardware in computer architecture, what is memory management in os, memory management hardware, storage management in operating system, memory management, memory protection, memory management in operating system pdf, what is memory management in operating system, what is memory management, memory management, etc....

Memory management requirements:

1. Relocation
2. Protection
3. Sharing
4. Logical Organization

5. Physical Organization

1. Relocation:

The programmer does not know where the program will be placed in memory when it is executed while the program is executing, it may be swapped to disk and returned to main memory at a different location (relocated). Memory references must be translated into the code to the actual physical memory addresses.

The address generated by the CPU is said to be a logical address. An address generated by MMU is called a physical address.

Physical address= Contents of Relocation register + logical address

2. Protection:
Processes should not be able to reference memory locations in another process without permission. It must be checked at run time. The memory protection requirement must be satisfied by the processor (hardware) rather than the operating system (software).

The word protection means provide security from unauthorized usage of memory. The operating can protect the memory with the help of base and limit register. Base registers consisting of the starting address of the next process. The limit specifies the boundary of that job, so the limit register is also said to be a fencing register.

3. Sharing:
Allow several processes to access the same portion of memory. It is better to allow each process access to the same copy of the program rather than have their own separate copy.

4. Logical organization:
Programs are written in modules. Modules can be written and compiled independently. Different degrees of protection given to modules (read-only, execute-only). Modules are shared among processes.

5. Physical organization:
Memory available for a program plus its data may be insufficient. Overlaying allows various modules to be assigned to the same region of memory.

Computer memory is organized into two levels:
Main memory and secondary memory. Main memory provides fast access at a relatively high cost and it is volatile that means it cannot provide permanent storage whereas secondary memory is slower and cheaper and it is a non-volatile object.

Virtual memory: A computer can address more memory than the amount physically installed on the system. This extra memory is actually called virtual memory and it is a section of a hard disk that's set up to emulate the computer's RAM.
The main visible advantage of this scheme is that programs can be larger than physical memory. Virtual memory serves two purposes. First, it allows us to extend the use of physical memory by using a disk. Second, it allows us to have memory protection because each virtual address is translated to a physical address.

Modern microprocessors intended for general-purpose use, a memory management unit, or MMU, is built into the hardware. The MMU's job is to translate virtual addresses into physical addresses. A basic example is given below −

Computer memory is organized into two levels

Virtual memory is commonly implemented by demand paging. It can also be implemented in a segmentation system. Demand segmentation can also be used to provide virtual memory.

Demand Paging:

A demand paging system is quite similar to a paging system with swapping where processes reside in secondary memory and pages are loaded only on demand, not in advance. When a context switch occurs, the operating system does not copy any of the old program’s pages out to the disk or any of the new program’s pages into the main memory Instead, it just begins executing the new program after loading the first page and fetches that program’s pages as they are referenced.

Free Space Management in Operating System - CodeTextPro

Hanif Miah 11:08 AM 0

Operating System

free space management in operating system or
Free space management of file system:
In this article, we will learn about free space management and some techniques to implement operating system list, free space management in os.

Since disk space is limited, we need to reuse the space from deleted files for new files, if possible.

To keep track of free disk space, the system maintains a free-space list.

The free-space list records all free disk blocks – those not allocated to some file or directory.

To create a file, we search the free-space list for the required amount of space and allocate that space to the new file.

This space is then removed from the free-space list.

When a file is deleted, its disk space is added to the free-space list.

We discuss here some techniques for free space management.

1. Bit vector or Bit table:

A bit vector is a collection of bits, in which each block is represented by one bit. If the block is free, the bit is 0.If the block is allocated, the bit is 1. For example consider a disk where blocks 5, 8, 16, 20 are free, the free space bit vector would be

2. Chain free points or Linked free space list:

Another approach is to link all the free space blocks together, keeping a pointer to the first free block. This block contains a pointer to the next free disk block and so on.

3. Indexed block list:

The chained or linked free portion is not very efficient since to traverse the list, we must read each block requiring substantial I/O time. A modification of this approach would store the address of n free blocks in the first free block.

The main advantage of this method is that the address of a large number of free blocks can be found quickly.

Important part of memory management

Definition of Segmentation:

Like Paging, Segmentation is also a memory management scheme. It supports the user’s view of the memory. The process is divided into the variable size segments and loaded to the logical memory address space.

The logical address space is the collection of variable size segments. Each segment has its name and length. For the execution, the segments from logical memory space are loaded to the physical memory space.

Wednesday, October 16, 2019

File Management in Operating System - CodeTextPro

Hanif Miah 4:27 PM 0

Operating System

File Management/File Management in Operating System:

File Management

In this content, you will know all about an file management, file system in os, file management in operating system, features of operating system, file management system, types of operating system notes, characteristics of operating system, file operations in os and more.

File management is one of the basic and important features of an operating system. The operating system is used to manage files of the computer system. All the files with different extensions are managed by the operating system.

To learn about more features of the operating system:

A file is a collection of specific information stored in the memory of the computer system. File management is defined as the process of manipulating files in the computer system, its management includes the process of creating, modifying and deleting the files.

File: A file is a collection of similar records with a common name. A record is a collection of related fields that can be treated as a unit by some application program.

File operation: The main operations that a user can perform on a file.
1. Open: Make the file available to the user.
2. Close: Relinquish access to an opened file.
3. Read: Read the data from a given location in the file.
4. Write: Write the data into the file at a given location.
5. Erase: To erase the contents of the file.
6. Append: Add data at the end of the file.
7. Seek: Move to the specified location in the file from the current position.
8. Rename: Modify the name of the file to a new name.
9. Delete: Delete the file name from the system by removing its directory entry.

10. Truncate: To truncate a file, remove the file contents only, but the attributes areas it is.

File attributes: Following are some of the attributes of a file:

Name. It is the only information that is in a human-readable form.

Identifier. The file is identified by a unique tag (number) within a file system.

Type. It is needed for systems that support different types of files.

Location. Pointer to file location on device.

Size. The current size of the file.

Protection. This controls and assigns the power of reading, writing, executing.

Time, date, and user identification. This is the data for protection, security, and usage monitoring.

File accessing techniques/methods:

Most important file accessing techniques are given below.
1. Sequential access.
2. Direct access.

3. Indexed sequential access.

Sequential access:

This method is the simplest of all methods. Information in the file is processed in order, one record after another. Magnetic tapes are supporting this type of file accessing. For example, consisting of 100 records, the current position of read/write head is 45th record, suppose we want to read the 75th record then it accesses sequentially from 45, 46, 47…….73,74,75.
So the read/write head traverse all records between 45 to 75. Consider the figure no 1 for better understanding.

Example: Sequential files are typically used in batch applications and payroll applications.

File Management Sequential access

Direct access:

Direct access is also called relative access. In this method, records can read/write randomly without any order. A direct access file allows arbitrary blocks to be read or written. For example, a disk consisting of 256 blocks, the current position of read/write head is at the 95th block. The block to be read or write is the 250th block. Then we can access the 250th block directly without any restrictions.

Example: The best example of direct access is a CD consisting of 10 songs, suppose at present we are listening to the song no: 3, suppose we want to listen the song no: 9 then we can shift from song no 3 to 9 without any restrictions.

Indexed sequential file:

This mechanism is built upon the base of sequential access.
An index is created for each file which contains pointers to various blocks.
An index is searched sequentially and its pointer is used to access the file directly.

File Management System Indexed sequential file

Suppose a file consisting of 60,000 records, the master index divides the total records into 6 blocks, each block consisting of a pointer to secondary index. The secondary index divide the 10,000 records into 10 indexes. Each index consisting of a pointer to its original location. Each record in the index file consisting of two fields. A key field and pointer field. Suppose we want to access the 55,550th record then the file management system accesses the index that is 50,000 to 60,000, this block consisting of a pointer, this pointer points to the 6th index in the secondary index.

This index points to the original location of the record from 55,000 to 56,000. From this, it follows the sequential method. That’s why this method is said to be the indexed sequential file.

Example: airline reservation system.

Deadlock Avoidance and Bankers Algorithm in OS

Hanif Miah 10:45 AM 0

Operating System

Deadlock Avoidance and Bankers Algorithm in OS

Deadlock avoidance/deadlock avoidance in os

It is one of the methods of dynamically escaping from the deadlocks. The word dynamically means ‘Online’. In this scheme, if a process request for resources the avoidance algorithm checks before the allocation of resources about the state of the system. If the state is safe the system allocates the resources to the requesting process otherwise (unsafe) do not allocate the resources. So taking care before the allocation is said to be deadlock avoidance.

Safe state: No deadlock will happen, even we allocate the resources to requesting processes.

Deadlock avoidance/deadlock avoidance in os

Deadlock

Banker’s algorithm /bankers algorithm

It is a deadlock avoidance algorithm, the name was chosen because the bank never allocates more than the available cash.
Multiple instances.
Each process must a priori claim maximum use.
When a process requests a resource it may have to wait.
When a process gets all its resources it must return them in a finite amount of time.

Data Structures for the Banker’s Algorithm

Data Structures for the Banker’s Algorithm

Safety Algorithm /Deadlock avoidance

Safety Algorithm for Banker’s algorithm

Example of Banker’s algorithm /banker's algorithm in os

banker's algorithm in os

Now, we have to calculate the available matrix of the resources.
Available = Total-Allocation
R1 = 10 - (2+3+2)=3
R2 = 5- (1+1) = 3
R3 = 7 – (2+1+2) = 2
Available matrix is (3,3,2)

Now the snapshot is modified:

banker's algorithm in os available matrix

Now we have to calculate the need matrix:

banker's algorithm in os need matrix

Now we know the need matrix and available matrix, so we can apply the banker’s algorithm on this example. Search the need matrix from P0 to P4 which is less than the available matrix, (1,2,2)<(3,3,2). Then allocate the requesting resource to P1. Now the process P1 may allocate (2,0,0+1,2,2)=(3,2,2).

After the completion of job P1, it releases the total resources, then available resource is (3,3,2+2,0,0)=(5,3,2).

Search the need matrix again, which is less than the available (0,1,1)<(5,3,2). To allocate resources to P3. after the completion of P3, it releases all its resources. Then the available =(available+allocation). It is (5,3,2+2,1,1)=7,4,3. continues this process until we find the safe state otherwise wait. The safe state sequence for this problem is <P1, P3, P4, P2, P0>.

Tuesday, October 15, 2019

Deadlock Detection and Recovery in OS - CodeTextPro

Hanif Miah 9:21 PM 0

Operating System

Deadlock detection

The detection mechanism of deadlocks for a single instance of the resource type and multiple instances of the resource type is different. We can detect the deadlocks using the wait-for graph for single instance resource type and detect using detection algorithm for multiple instances of the resource type.

Single Instance of resource type: a single instance of resource type means, the system consisting of only one resource for one type. We can detect this type of deadlocks with the help of the wait-for graph. A wait-for graph is a graph, it is derived from “Resource-Allocation Graph”. It is consisting of only processes as vertices instead of, resources and processes in the resource-allocation graph.

Deadlock Detection and Recovery

An edge from Pi to Pj in a wait-for graph implies that process Pi is waiting for process Pj to release a resource that Pi needs. An edge Pi to Pj exists in a wait-for graph if and only if the corresponding resource allocation graph contains two edges Pi to Rq and Rq to Pj for some resource Rq.

For example, consider the previous figure. We represent a RAG and corresponding Wait-for graph. A system is in deadlock state, if and only if the wait for graph contains cycles. So we can detect the deadlocks with cycles. In the figure, there are 2 cycles one is P1 to P2 to P1. second one P2 to P3 to P2. so the system consisting of two deadlocks.

Deadlock detection –several instances of resource type:

The wait-for graph method is not applicable to several instance of the resource type. So we need another method for this type that is the “Deadlock Detection Algorithm”. This algorithm looks like “Banker’s Algorithm” and its employee's several data structures that are similar to those used in the Bankers Algorithm.

Data Structures:

Available: A vector of length m indicates the number of available resources of each type.

Allocation: An n x m matrix defines the number of resources of each type currently allocated to each process.

Request: An n x m matrix indicates the current request for each process. If Request [ij] = k, then process Pi is requesting k more instances of the resource type. Rj.

Detection Algorithm

Example of Detection Algorithm

Five processes P0 through P4; three resource types A (7 instances), B (2 instances), and C (6 instances).

Snapshot at time T0:

State of the system?

Can reclaim resources held by process P0, but insufficient resources to fulfill other processes; requests.

A deadlock exists, consisting of processes P1, P2, P3, and P4.

Recovery from Deadlock

There are two methods for breaking a deadlock. One solution is simply to abort one by one processes to break the circular wait. The second option is to preempt some resources from one or more of the deadlocked processes.

Process Termination:

It is one method to recover from deadlock. We use one of two methods for process termination, these are:

Abort all deadlocked processes: It means to release all processes in the deadlocked state, and start the allocation from the starting point. It is a great expensive method.

Abort one by one process until the deadlock cycle is eliminated: In this method first abort one of the processes in the deadlocked state, and allocated the resources ( resource from abort process) to some other process in the deadlocked state then check whether the deadlock is breaked or not. If not abort another process from the deadlock state. Continue this process until we recover from deadlock. This method is less expensive than first.

Resource Preemption:
There are three methods to eliminate deadlocks using resource preemption, these are:

Selecting a Victim: Select a victim resource from the deadlock state, and preempt that one. Minimize cost.

Rollback: Rollback the processes and resources unto some safe state, and restart it from that state. This method requires the system to keep more information about the state of all the running processes. Return to some safe state, restart the process for that state.

Starvation: A process (or) resources can be picked as a victim only a finite number of times, it is said to be starvation. The most common solution is to include the number of rollbacks in the cost factor. the same process may always be picked as the victim, include number of rollback in the cost factor

Fundamentals of Cartoon: Best Way to Draw Cartoon | How to Draw a Cartoon Character Correctly

Hanif Miah 3:00 PM 0

drawing

Fundamentals of Cartoon: Best Way to Draw Cartoon | How to Draw a Cartoon Character Correctly

Cartoon Designing Basic:

There are many ways to design or drawing a cartoon. I discuss the easy ways to draw cartoons step by step for beginners to draw the cartoon character by himself. If you read the step by step process then you will completely learn how to designing cartoon characters. If you learn this simple drawing process, you can make many characters like- cartoon design birthday cake, cartoon mehndi design, cartoon designing, carton box design, cartoon design t-shirt, cartoon ka design, cartoon design drawing, cartoon designing courses, cartoon designing app, cartoon design for wall, cartoon design wallpaper, cartoon design sweater, cartoon designing software, software for cartoon design, cartoon design bed sheet, cartoon design for tshirt, cartoon design shoes, cartoon room design, cartoon design wale, etc..

how to draw a cartoon girl for beginners

Drawing Inspiration: Getting Started with Cartoons and Comics

Doing rough sketches

Rough sketches are the visual note-taking of the cartoon world. Rough sketches should be just what they say they are — rough. Don’t spend too much time on them, because they’re just meant to capture the basic idea and layout of your composition so you have it when you want to develop the idea further. Making rough sketches doesn’t require you to follow any specific rules.

Rough sketches may be little more than a series of stick figures or other loose scribbles quickly jotted down on a scrap piece of paper or on the back of an envelope.

Tightening up your Sketch

Tightening up a sketch means to define the lines so that the characters, word balloons, background, and overall composition are clearer and more defined. This is the stage when the final composition comes into focus and you can see how the line art will look prior to beginning the inking process.

When you tighten up your sketch, you simply go over your first loose sketch and darken it up while further defining the characters. This is the stage where your drawings become cleaner and come into focus.

Inking

1. Before using your new brush, dip it in a brush cleaner and twirl the end so that it acquires a sharp pointed edge.

2. After you’re satisfied that the brush tip is nice and sharp, dip about 3/4of the brush into an open ink bottle so that you pick up a sufficient amount of ink.

3. To draw a thin line, apply the brush to the paper using a light amount of pressure.

4. To make your line thicker, just add more pressure.

Creating Tone and Texture

Tone and texture can add depth and help a flat drawing look more dimensional. Because cartoons deal primarily with black-and-white line art, utilizing techniques such as shading and crosshatching create tone and texture.

Tone and texture help define the shape you’re drawing and add depth to the art. Without tone and texture, the line art looks flat and bare and may not covey the right perspective, dimension, or relationship to the other elements drawn around it. This section shows you how to do both techniques.

Shading

You can use shading to add depth and dimension to your sketch. Shadings the process of darkening an area of your sketch to give the impression of depth.

With a Pencil

Shading with a pencil is pretty straightforward. If you draw a cube with a pencil, shading the cube on one side to add depth is easy because a pencil is a soft medium and is able to produce gray, shade-type tones. To shade with a pencil, use the side of the pencil lead. Doing so creates a softer line quality as you move it back and forth in the area you’re shading.

With ink

Ink is solid and reproduces as a dark solid value when it’s printed. To shade with ink, simply fill in the area you’re shading so that it’s totally black. This can create a dramatic light/dark effect. Don’t do this, however, if you need some tonal gradation in the

area you’re shading, because it will be uniformly dark.

With Washes

Washes are methods that have been used for hundreds of years to create shade and tonal value in illustrations and other art destined for newsprint. Washes, which are gray in color, are used to shade an illustration. Washes are generally ink that’s been watered down until it’s a much lighter, transparent consistency. To apply a wash, you use a watercolor brush to dip into the wash and cover over the areas you want to shade, usually on a watercolor-based paper. To achieve the right gray shade, mix water in with a small amount of ink until you get the shade you want.

The results of washes are very similar to watercolor except that washes are always some shade of gray. The technique is still very much in use in cartoons that are regularly published in The New Yorker magazine, among others. The technique results in a toned-down, more sophisticated looking composition.

Crosshatching

If you want to create a tonal quality using black and white, you can use a technique called crosshatching. Just as the name implies, crosshatching means to draw vertical lines in one direction and then cross over them with diagonal or horizontal lines.

Crosshatching is a technique best suited for applications in which other forms of shading may not reproduce well. This is especially true with regard to newsprint.

news-papers have a tendency to run images smaller than the cartoonist originally intended. If you color your art or use a watercolor wash, when the image is reduced down and reproduced on the page, the shading technique fails as the area appears solid and the image may lose any tonal quality.

Crosshatching creates a darker tone but not a solid one. You can vary your tones by changing the number of lines you draw and where you place them.

Ideas

1.Newspaper and magazine articles.

2.TV news.

3. Things your parents did, once upon a time — start really listening to their stories!

4. Things your kids do — really, they’re funny in retrospect.

5. Things your pets do — ditto!

6. Your own childhood memories.

7. Funny conversations — we all have them, it’s just a matter of remembering them.

8. Interesting situations or experiences (we all have these, too).

9. Fascinating people you know or meet.

10. Tragic events (yes, tragedy can be funny, if it’s handled right).

11. Mundane activities of life — remember, it’s all about the spin you put

on things.

Writing Believable Story Lines

Writing funny storylines creates characters that people can not only turn to for comic relief but also will become attached to overtime. Interesting storylines allow your characters to develop into individual voices that, when separated from the bunch, can offer insight and subtle humor, but together offer real synergy. In other words, the sum is greater than the parts.

Whether your comic strip appears in the newspaper or on the Web, you may have to create a new storyline on a daily basis. Because maintaining a believable level of constant hilarity is almost impossible, the humor you inject will probably be more subtle than slapstick. Some points you may want to consider when writing humorous storylines include:

Write storylines that draw upon the characters’ strengths or weaknesses.
Write storylines based on common humorous themes and ideas that readers can relate to and recognize in their own life.
Write storylines that are funny but not too abstract.
Don’t write storylines that require the reader to have read yesterday's cartoon in order to understand the one you wrote today.
Don’t write storylines that are too conceptual.

DRAWING METHOD 1:

DRAWING METHODS FROM THE CAST OR FROM LIFE

I. First of all the artist needs to locate the center of the paper. This can be done by drawing lines from corner to corner to help center the study.

2. With one's eye or using a pencil one can measure to locate the center o the subject and then make a line at that point in relation to the center of the paper. Using free lines the artist must search for the rhythm of the pose to aid in visualizing the figure and for placing it on the paper with the required size. The drawing must be light so as not to erase the mental impression by a heavy illustration. Due to this, corrections can be easily made.

3. Then the artist must decide where the pit of the neck is to be placed. Then a perpendicular line can be drawn from this point (in case of a front view to the feet. In the case of a back view, the perpendicular line must be drawn from the seventh cervical vertebra to the feet. The line of the shoulders must be located to give the angle of their positions. In the case of a standing figure, the leg must be drawn first, on which there is most weight. This helps to get the proper balance of the figure.

4. Now the line showing the angle of the position of the pelvis must be given. A line must be drawn through to indicate the knee caps. Now the torso must be drawn to indicate its bulk and mark the width of the head, neck. hips and shoulders. The artist must block with straight lines that go beyond the intersections. This must be done to get a better idea of the line's direction and to get away from the cramped feeling.

5. Sketching within the lines of a simplified skeleton aids in checking up the position of the bulk of chest and joints. The artist must see that the inner ankles, knee, caps, pelvis, navel, pubic bone and the pit of the neck are in correct relation to each other. The relative sizes of leg, arm, head to that of the neck's thickness, head to the bulk of torso, feet to hands, arms to legs and hands to face must be compared.

6. The artist needs to go over the outline, perfecting it to search for character and achieve the grace of line.

7. The outlines of planes and the principal shadows must be indicated.

8. The planes need to be filled in large surfaces. The shadows must be connected as much as possible.

9. The planes must be modeled, without losing their mass and remembering the direction of light. When drawing the head the bulk must be decided. Then the artist must draw in the planes of the face followed by the eyes. mouth and nose. Remember, it is easier to put a head on a figure as compared to putting a figure on ahead.