Difference between revisions of "Scilab/C2/Iteration/English-timed"
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− | || ''Time''' | + | || '''Time''' |
|| '''Narration''' | || '''Narration''' | ||
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− | |00 | + | |00:01 |
| | Welcome to the spoken tutorial on iterative calculations using Scilab. | | | Welcome to the spoken tutorial on iterative calculations using Scilab. | ||
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| | I am using scilab version 5.2 in Mac operating system , | | | I am using scilab version 5.2 in Mac operating system , | ||
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− | | 00 | + | | 00:11 |
| | but these calculations should work in other versions and also in Scilab that runs in linux and windows. | | | but these calculations should work in other versions and also in Scilab that runs in linux and windows. | ||
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| | I will use the code available in the file iteration.sce | | | I will use the code available in the file iteration.sce | ||
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|| I have opened this file using Scilab editor, which I plan to use only as an editor. | || I have opened this file using Scilab editor, which I plan to use only as an editor. | ||
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− | | 00 | + | | 00:29 |
|| Let us create a vector using the colon operator i is equal to 1 colon 5. | || Let us create a vector using the colon operator i is equal to 1 colon 5. | ||
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| |creates a vector from 1 to 5, in increments of 1. | | |creates a vector from 1 to 5, in increments of 1. | ||
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| | In this command, i is equal to 1 colon 2 colon 5, | | | In this command, i is equal to 1 colon 2 colon 5, | ||
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| | We see that the middle argument of 2 indicates the increment. | | | We see that the middle argument of 2 indicates the increment. | ||
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| | 1 is the first argument where the vector starts. I cannot go beyond 5. | | | 1 is the first argument where the vector starts. I cannot go beyond 5. | ||
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| |It can be equal to 5, however. | | |It can be equal to 5, however. | ||
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| | Note that if the ending argument changes to 6 the result remains the same. | | | Note that if the ending argument changes to 6 the result remains the same. | ||
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| | It is not difficult to explain this behaviour. | | | It is not difficult to explain this behaviour. | ||
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| Can you think for a moment why this happens? | | Can you think for a moment why this happens? | ||
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|We will now demonstrate the use of the for statement to perform iterative calculations. | |We will now demonstrate the use of the for statement to perform iterative calculations. | ||
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|for i is equal to 1 colon 2 colon 7 disp i end of for loop. | |for i is equal to 1 colon 2 colon 7 disp i end of for loop. | ||
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| |I will cut this paste in scilab console press enter. | | |I will cut this paste in scilab console press enter. | ||
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| |This code prints out i, as we go through the loop. | | |This code prints out i, as we go through the loop. | ||
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| |The display is due to the command disp - the passed argument is displayed. | | |The display is due to the command disp - the passed argument is displayed. | ||
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| |Recall that the for loop is used for integer values. | | |Recall that the for loop is used for integer values. | ||
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| | In this case, four integer values, namely, 1, 3, 5 and 7 are displayed. | | | In this case, four integer values, namely, 1, 3, 5 and 7 are displayed. | ||
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| |The number of times the iterations take place is known as priori in for loops. | | |The number of times the iterations take place is known as priori in for loops. | ||
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| | In the rest of this tutorial, we will stick to the default increment of 1. | | | In the rest of this tutorial, we will stick to the default increment of 1. | ||
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| |Let us begin with the loop that displays i equal to 1 to 5. | | |Let us begin with the loop that displays i equal to 1 to 5. | ||
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| | We will modify this code by introducing the break statement. | | | We will modify this code by introducing the break statement. | ||
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| Note that i is displayed only up to 2. | | Note that i is displayed only up to 2. | ||
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| | The iteration is not carried out till the last value of i, namely 5. | | | The iteration is not carried out till the last value of i, namely 5. | ||
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| | When i is equal to 2, the if block is executed for the first time. | | | When i is equal to 2, the if block is executed for the first time. | ||
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| | The break command, however, terminates the loop. | | | The break command, however, terminates the loop. | ||
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|| If we want to get out of a loop when some intermediate condition is satisfied, we can use the break statement. | || If we want to get out of a loop when some intermediate condition is satisfied, we can use the break statement. | ||
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| | Note that "i is equal to 2" statement uses the "equal to" sign twice. | | | Note that "i is equal to 2" statement uses the "equal to" sign twice. | ||
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| | This is the standard way to compare the equality in programming languages. | | | This is the standard way to compare the equality in programming languages. | ||
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| | The result of this comparison statement is a boolean: true or false. | | | The result of this comparison statement is a boolean: true or false. | ||
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| | We will introduce the continue statement here paste press enter | | | We will introduce the continue statement here paste press enter | ||
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|| This results in i getting displayed only for 4 and 5. | || This results in i getting displayed only for 4 and 5. | ||
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| | For i less than or equal to 3, as given by the i less than or equal to 3 statement, nothing happens. | | | For i less than or equal to 3, as given by the i less than or equal to 3 statement, nothing happens. | ||
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| | The continue statement makes the program skip the rest of the loop. | | | The continue statement makes the program skip the rest of the loop. | ||
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| Unlike the break statement, however, it does not exit the loop. | | Unlike the break statement, however, it does not exit the loop. | ||
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| | The parameter i is incremented and all the calculations of the loop are executed for the new i. | | | The parameter i is incremented and all the calculations of the loop are executed for the new i. | ||
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| | We take a small break and show how to get help for operators of the type less than or equal to. | | | We take a small break and show how to get help for operators of the type less than or equal to. | ||
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| |Let us type less than or equal to with help | | |Let us type less than or equal to with help | ||
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|| This opens the scilab help browser. | || This opens the scilab help browser. | ||
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|| We see that the help is available under the option less. | || We see that the help is available under the option less. | ||
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| | So now after closing this we type help less | | | So now after closing this we type help less | ||
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|| We see the required help instructions here. I will close this. | || We see the required help instructions here. I will close this. | ||
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| | The for statement in Scilab is more powerful than in programming languages. | | | The for statement in Scilab is more powerful than in programming languages. | ||
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| | For example, let us perform a loop over a vector: | | | For example, let us perform a loop over a vector: | ||
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| | This script displays all values of v. | | | This script displays all values of v. | ||
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| | Until now we have been displaying only the variables. | | | Until now we have been displaying only the variables. | ||
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| | We can indeed display the result of a calculation as well. | | | We can indeed display the result of a calculation as well. | ||
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| | The following code displays the square of the numbers. | | | The following code displays the square of the numbers. | ||
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| | We have spent quite a bit of time explaining the for loop. | | | We have spent quite a bit of time explaining the for loop. | ||
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| | Let us now move on to the while loops. | | | Let us now move on to the while loops. | ||
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| | The while statement allows us to perform a loop when a boolean expression is true | | | The while statement allows us to perform a loop when a boolean expression is true | ||
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| | At the beginning of the loop, if the expression is true, | | | At the beginning of the loop, if the expression is true, | ||
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| |the statements in the body of the while loop are executed. | | |the statements in the body of the while loop are executed. | ||
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| | If the program is written well, the expression becomes false and the loop is ended. | | | If the program is written well, the expression becomes false and the loop is ended. | ||
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|| Now let us see an example for the while loop: | || Now let us see an example for the while loop: | ||
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| | The values of i, from 1 to 6 are displayed. | | | The values of i, from 1 to 6 are displayed. | ||
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|| Break and continue statements inside the while loop work exactly as they did in the for loop, as we demonstrate using break: | || Break and continue statements inside the while loop work exactly as they did in the for loop, as we demonstrate using break: | ||
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| | We can see that the moment i becomes equal to 3, the program exits the loop, thanks to the break statement. | | | We can see that the moment i becomes equal to 3, the program exits the loop, thanks to the break statement. | ||
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|| You can also try the example for continue statement in while loop. | || You can also try the example for continue statement in while loop. | ||
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| | This brings us to the end of this spoken tutorial on iterative calculations using Scilab. | | | This brings us to the end of this spoken tutorial on iterative calculations using Scilab. | ||
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|| Spoken Tutorials are part of the Talk to a Teacher project, supported by the National Mission on Education through ICT. | || Spoken Tutorials are part of the Talk to a Teacher project, supported by the National Mission on Education through ICT. | ||
|- | |- | ||
− | | 05 | + | | 05:57 |
| | More information on the same is available at the following link [http://spoken-tutorial.org/NMEICT-Intro]. | | | More information on the same is available at the following link [http://spoken-tutorial.org/NMEICT-Intro]. | ||
|- | |- | ||
− | | 06 | + | | 06:00 |
| |Thanks for joining.Good bye. | | |Thanks for joining.Good bye. | ||
|} | |} |
Revision as of 17:00, 10 July 2014
Time | Narration |
00:01 | Welcome to the spoken tutorial on iterative calculations using Scilab. |
00:07 | I am using scilab version 5.2 in Mac operating system , |
00:11 | but these calculations should work in other versions and also in Scilab that runs in linux and windows. |
00:17 | I will use the code available in the file iteration.sce |
00:22 | I have opened this file using Scilab editor, which I plan to use only as an editor. |
00:29 | Let us create a vector using the colon operator i is equal to 1 colon 5. |
00:38 | creates a vector from 1 to 5, in increments of 1. |
00:42 | In this command, i is equal to 1 colon 2 colon 5, |
00:51 | We see that the middle argument of 2 indicates the increment. |
00:56 | 1 is the first argument where the vector starts. I cannot go beyond 5. |
01:01 | It can be equal to 5, however. |
01:04 | Note that if the ending argument changes to 6 the result remains the same. |
01:09 | It is not difficult to explain this behaviour. |
01:13 | Can you think for a moment why this happens? |
01:15 | We will now demonstrate the use of the for statement to perform iterative calculations. |
01:22 | for i is equal to 1 colon 2 colon 7 disp i end of for loop. |
01:28 | I will cut this paste in scilab console press enter. |
01:34 | This code prints out i, as we go through the loop. |
01:37 | The display is due to the command disp - the passed argument is displayed. |
01:42 | Recall that the for loop is used for integer values. |
01:45 | In this case, four integer values, namely, 1, 3, 5 and 7 are displayed. |
01:50 | The number of times the iterations take place is known as priori in for loops. |
01:56 | In the rest of this tutorial, we will stick to the default increment of 1. |
02:01 | Let us begin with the loop that displays i equal to 1 to 5. |
02:10 | We will modify this code by introducing the break statement. |
02:18 | Note that i is displayed only up to 2. |
02:22 | The iteration is not carried out till the last value of i, namely 5. |
02:27 | When i is equal to 2, the if block is executed for the first time. |
02:30 | The break command, however, terminates the loop. |
02:34 | If we want to get out of a loop when some intermediate condition is satisfied, we can use the break statement. |
02:40 | Note that "i is equal to 2" statement uses the "equal to" sign twice. |
02:45 | This is the standard way to compare the equality in programming languages. |
02:50 | The result of this comparison statement is a boolean: true or false. |
02:56 | We will introduce the continue statement here paste press enter |
03:06 | This results in i getting displayed only for 4 and 5. |
03:10 | For i less than or equal to 3, as given by the i less than or equal to 3 statement, nothing happens. |
03:18 | The continue statement makes the program skip the rest of the loop. |
03:22 | Unlike the break statement, however, it does not exit the loop. |
03:25 | The parameter i is incremented and all the calculations of the loop are executed for the new i. |
03:32 | We take a small break and show how to get help for operators of the type less than or equal to. |
03:38 | Let us type less than or equal to with help |
03:46 | This opens the scilab help browser. |
03:51 | We see that the help is available under the option less. |
03:56 | So now after closing this we type help less |
04:06 | We see the required help instructions here. I will close this. |
04:11 | The for statement in Scilab is more powerful than in programming languages. |
04:16 | For example, let us perform a loop over a vector: |
04:24 | This script displays all values of v. |
04:28 | Until now we have been displaying only the variables. |
04:32 | We can indeed display the result of a calculation as well. |
04:35 | The following code displays the square of the numbers. |
04:44 | We have spent quite a bit of time explaining the for loop. |
04:48 | Let us now move on to the while loops. |
04:50 | The while statement allows us to perform a loop when a boolean expression is true |
04:55 | At the beginning of the loop, if the expression is true, |
04:58 | the statements in the body of the while loop are executed. |
05:02 | If the program is written well, the expression becomes false and the loop is ended. |
05:08 | Now let us see an example for the while loop: |
05:15 | The values of i, from 1 to 6 are displayed. |
05:19 | Break and continue statements inside the while loop work exactly as they did in the for loop, as we demonstrate using break: |
05:33 | We can see that the moment i becomes equal to 3, the program exits the loop, thanks to the break statement. |
05:39 | You can also try the example for continue statement in while loop. |
05:44 | This brings us to the end of this spoken tutorial on iterative calculations using Scilab. |
05:50 | Spoken Tutorials are part of the Talk to a Teacher project, supported by the National Mission on Education through ICT. |
05:57 | More information on the same is available at the following link [1]. |
06:00 | Thanks for joining.Good bye. |