Difference between revisions of "Scilab/C2/Getting-Started/English-timed"

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|We can also assign the answer to another variable say 'd' by typing d = bracket a+b close the bracket multiplied by c gives the answer  
 
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| For complex numbers you can check this for yourself type : log of -1 or log of %i on your scilab console.
 
| For complex numbers you can check this for yourself type : log of -1 or log of %i on your scilab console.
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|Now, let's see how to close that file and view it.  
 
|Now, let's see how to close that file and view it.  
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Revision as of 16:20, 10 July 2014

Time Narration
00:02 Welcome to the spoken tutorial on Getting Started with Scilab.
00:07 In this tutorial we are going to learn:
00:09 The use Scilab as a calculator.
00:12 How to Store values in a variable.
00:15 How to Perform various mathematical operations using these variables.
00:21 How to Create a file to store commands executed during the session in the current working directory.
00:29 How to define complex numbers.
00:31 How to Perform exponential, logarithmic and trigonometric operations on numbers.
00:38 The prerequisite for this tutorial are Scilab should be installed on your computer.
00:44 I am using Scilab 5.2.0 and Mac OS/X for demonstration
00:51 Here is the Flow chart for the tutorial.
00:55 Click on the Scilab shortcut icon on your Desktop and Start Scilab.
01:01 This is the Scilab console window. Notice that the cursor is on the command prompt.
01:07 I suggest that you practice this tutorial in Scilab simultaneously while pausing the video at regular intervals of time.
01:16 Scilab can be used as a calculator.
01:19 Let us see some of the basic operations that it can do.
01:25 Type 42 plus 4 multiplied by 4 minus 64 divided 4 and press enter.
01:36 The output is 42, as expected.
01:39 Note that the answer 42 is stored in the default variable "a n s".
01:45 We can also create named variables: Type,
01:49 a equals 12, b=21 , c=33 and press enter.
02:00 This stores the values 12, 21 and 33 in the variables a, b and c respectively.
02:08 I will clear the scilab console using the clc command here
02:13 Now we will perform some mathematical operations using these variables.
02:19 For example,
02:21 a+b+c gives the result 66
02:27 also
02:29 a times into bracket
02:35 b plus c gives the result 648
02:41 We can also assign the answer to another variable say 'd' by typing d = bracket a+b close the bracket multiplied by c gives the answer
02:58 d = 1089.
03:01 We can check the values in the variables by typing the names of the variables separated by commas on the command line as
03:09 a,b,c,d and press enter
03:16 I will clear the console here using the clc command
03:21 To take the power, use the “raised to” symbol which is located on the number key 6 of your keyboard.
03:29 Press ' shift key' and number key 6 to used this symbol.
03:34 for example, 7 square can be found by 7 raised to 2 and press Enter.
03:43 For finding the square root of a number, say, 17, we use : sqrt of 17
03:55 This is same as 17 raised to the power of zero point five.
04:06 By convention, only the positive value comes as output.
04:10 More generally, to find 34 to the power of (2 by 5), type:
04:15 34 raised to bracket 2 divide by 5 close the bracket and press Enter.
04:25 Negative powers can also be used,
04:28 Clear the cansole using clc command
04:33 So far, you have seen how to do some simple calculations and how to create variables in Scilab.
04:40 Now let us start with the new command.
04:43 This will helps remember command which were previously issued along with the outputs.
04:49 First type the command pwd and press Enter
04:55 This is the current working directory (on my computer).
04:58 It might be different on your computer
05:01 The current working directory can be changed by clicking the changed current directory icon located on the toolbar of the scilab console window as you see.
05:15 Now issue the diary command by typing:
05:20 diary bracket, open inverted commas, myrecord.txt close inverted commas, close the bracket and press enter
05:40 This command will create a file with the name "myrecord.txt" in the current working directory.
05:48 A transcript of the Scilab session from now onwards will be saved in this file.
05:53 Its usefulness will be demonstrated at a later stage in this tutorial.
06:00 Please pause the tutorial now and attempt exercise number one given with the video.
06:07 Now, let us see how Scilab handles complex numbers.
06:13 The imaginary unit i is defined in Scilab as percent i:
06:18 For example,Five point two multiplied percent i gives 5.2i
06:29 also bracket 10 plus 5 into percent i whole multiply by 2 times percent i gives the result -10. + 20.i
06:58 Now clear the console here,
07:04 Let us see some other predefined numerical constants available in Scilab.
07:09 As with i, their names also start with the percent sign:
07:13 For example, percent pi.
07:18 The value of pi is as expected.
07:21 Now, we will demonstrate the use of pi using a few built-in trigonometric functions as follows.
07:27 For the functions sin of percent pi by 2 the result is 1
07:37 And for cos of percent pi by 2 the result is 6.123D-17.'
07:50 Please note that the angles are measured in radians and
07:54 Notice that the second answer is zero for all practical purposes.
07:59  %eps is related to number known as "machine epsilon",
08:03 It is the minimum digit resolution that Scilab can give.
08:08 Type % eps on your console to find its value on your computer.
08:19 On my computer it gives 2.220D-16
08:24 This shows the floating point precision used by Scilab .
08:28 This number is a notation for 2.22 times 10^(-16). Clear the console here.
08:41 If one wants to write 0.000456, one can write it as 4.56d-4 or 4.56e-4.
09:06 While scilab variables and functions are case-sensitive, here we can use small d or capital D, or small e, or capital E.
09:16 The base of the natural logarithm is another important predefined numerical constant:
09:22 percent e gives the result as expected.
09:30 We can achieve the same result with the function "e x p.
09:35 For example: exp bracket (1) close the bracket and press Enter
09:44 You can see both the answers are same
09:47 Clear the console using the clc command here.
09:55 similarly,
09:56  %e square gives the following answer
10:04 which can also be achieved by typing exp of 2 .
10:18 The command log means the natural logarithm of a number, that is, to the base e.
10:23 Use log 10 for taking the logarithm with respect to base 10.
10:29 For example, log10 bracket 1e minus 23 close bracket and press enter this gives the expected answer -23.
10:47 We get complex numbers when taking logarithm of negative.
10:51 For complex numbers you can check this for yourself type : log of -1 or log of %i on your scilab console.
11:01 Now recall that we invoked a recording of all the typed commands into the file myrecord.txt through the diary command,
11:09 Now, let's see how to close that file and view it.
11:13 For closing the file, type,
11:16 diary of zero
11:21 This command will close and save the file myrecord.txt.
11:26 Also recall that this file was created in current working directory, which in my case is desktop.
11:34 Let us open this file to do click on the a Open-a-file shortcut icon on your scilab console window toolbar.
11:46 I will change the file format to all file
11:51 Select the file myrecord.txt and click on Open.
11:59 Note that all transactions, both commands and the corresponding answers given by Scilab, have been saved into this file.
12:10 I will close this file.
12:15 Click yes.
12:21 We know that, while a program is being developed, one experiments a lot with the code before arriving at suitable code.
12:29 Diary command helps to keep track of all the transactions.
12:35 If you recall that, we had closed the file my record.txt using the command diary of zero.
12:42 Please , note that no transactions can be saved after executing this command.
12:48 If we need to save the session once again, we need to issue the diary command again.
12:54 If the file contains some useful information, then one should use the some other file name in the diary command.
13:03 Because, use of same file name will overwrite the existing file.
13:09 Pause the video here and solve the second exercise given with the video.
13:15 You may have noticed that the solution for the problem was not exactly zero.
13:21 For more information on how to deal with this, type “help clean”.
13:27 In general, if you need help about a particular command, then the 'help' or help with an argument command can be used.
13:37 For example, type “help chdir” on the scilab console and press enter.
13:53 I will increase the size of the help browser.
14:01 Help chdir gives detailed information on how to change the current working directory.
14:10 Another option is to click on the help browser icon on the toolbar of the scilab console window as you see.
14:20 Let me close the help browser and coming back to the slides.
14:31 The up - down arrow keys can been used to see the previously executed commands.
14:36 While using the up - down arrows, you can stop at any command,and press Enter to execute it.
14:45 You can edit the commands, if necessary.
14:48 In fact, you are looking for a previous command you typed, which started with the letter 'e', then type e, and then use up arrow key.
14:59 Use tab key to auto-complete the commad. It gives us all the available options to choose.
15:07 In this tutorial we have learnt :
15:10 Use of Scilab as a calculator .
15:12 Store the result in the default variable ans.
15:16 Assign values to the variable using the equality sign.
15:20 Check values in variables by typing the name of the variable separated by commas on the console.
15:28 Check the current working directory using pwd command.
15:34 Use diary command to save all commands typed on the console into a file.
15:40 Define complex numbers, natural exponents and π using %i, %e and %pi respectively.
15:49 Use help command for detailed information about any command.
15:54 This brings us to the end of this spoken tutorial on Getting Started with Scilab.
15:59 There are many other functions in Scilab which will be covered in other spoken tutorials.
16:06 This spoken tutorial has been created by the Free and Open Source Software in Science and Engineering Education(FOSSEE).
16:14 More information on the FOSSEE project could be obtained from http://fossee.in or http://scilab.in website
16:22 Supported by the National Mission on Eduction through ICT, MHRD, Government of India.
16:29 More information on this please visit spoken hyphen tutorial dot org slash NMEICT hyphen intro
16:43 I hope you find this spoken tutorial useful for learning.
16:47 Thank you.
16:48 This is Anuradha Amrutkar from IIT Bombay signing off.

Contributors and Content Editors

Gaurav, Jyotisolanki, Krupali, PoojaMoolya, Sandhya.np14, Sneha

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