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

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Revision as of 16:55, 10 December 2013

Visual Cue Narration
00.03 Welcome to the spoken tutorial on Getting Started with Scilab.
00.07 In this tutorial we are going to learn:
00.10 The use Scilab as a calculator.
00.13 How to Store values in a variable.
00.16 How to Perform various mathematical operations using these variables.
00.22 How to Create a file to store commands executed during the session in the current working directory.
00.29 How to define complex numbers.
00.32 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.
00.45 I am using Scilab 5.2.0 and Mac OS(X) for demonstration
00.52 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.
01.17 Scilab can be used as a calculator. 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.
01.40 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 , and 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
02.14 Now we will perform some mathematical operations using these variables.
02.20 For example,
02.21 a+b+c gives the result 66
02.27 also
02.29 a times into bracket (b+c) gives the result 648
02.42 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.
03.02 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
03.22 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.
03.44 For finding the square root of a number, say, 17, we use : sqrt(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) and press Enter.
04.25 Negative powers can also be used,
04.28 Clear the cansole using clc command
04.34 So far, we have seen how to do some simple calculations and how to create variables in Scilab.
04.41 Now let us start with the new command.
04.44 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).
04.59 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
05.41 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:
06.19 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.
07.28 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",
08.04 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.
09.17 The base of the natural logarithm is another important predefined numerical constant:
09.23 percent e gives the result as expected.
09.31 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
09.45 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.
10.24 Use log 10 for taking the logarithm with respect to base 10.
10.29 For example, log10(1e-23) and press enter this gives the expected answer -23.
10.47 We get complex numbers when taking logarithm of negative. For complex numbers you can check this for yourself type : log(-1) or log(%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, now, let's see how to close that file and view it.
11.14 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,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 have 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.
13.24 For more information on how to deal with this, type “help clean”.'
13.28 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 detained 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 the Enter to execute it.
14.45 You can edit the commands, if necessary.
14.48 In fact, if 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 the tab key to auto-complete the commad. It gives us all the available options to choose.
15.08 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.
15.21 Check values in variables by typing the name of the variable separated by commas on the console.
15.29 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
16.23 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 o r g 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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