1.4.4. Selective worksheet output

Suppose you have been working on a lengthy SCILAB session whose command history buffer contains some results that produced errors as well as some intermediary results that are not of interest to you for output. For your output, you can select only those commands relevant to your final results by using Cntl-P and Cntl-N.

In SCILAB, your session automatically keeps track of all commands you've entered. However, when you want to document or review your results, not all of these commands may be relevant. Some may have resulted in errors or intermediary steps that are cluttering your output. To create a clean report of only the important commands and their results, you can navigate through your command history using the shortcuts Cntl-P (to go back) and Cntl-N (to go forward). This allows you to selectively choose the commands you want to include in your output.

Think of it like sorting through a stack of papers where some sheets have notes you want to keep, while others are mistakes or drafts you don’t need. By going through and picking only the valuable pages, you create a neat, organized document that is easier to reference.

Try the following SCILAB session that explores some basic vector operations using vectors x and y: 1 - Press the Restart option in the menu bar. 2 - Enter the following SCILAB commands: -->x = [1, 2, 5, -4] x = ! 1. 2. 5. - 4. ! -->y = [0, 2, 3,-5] y = ! 0. 2. 3. - 5. ! -->x*y !--error 10 inconsistent multiplication -->x.*y ans = ! 0. 4. 15. 20. ! -->sum(ans) ans = 39. -->sum(x.y) ans = 39. -->xy' ans = ! 39. ! -->x'*y ans = ! 0. 2. 3. - 5. ! ! 0. 4. 6. - 10. ! ! 0. 10. 15. - 12. ! ! - 5. - 10. - 25. 20. !

In this example, you initiate a SCILAB session with defined vectors x and y. You explore various operations with these vectors. For instance, you first try a multiplication that results in an error due to incompatible dimensions, showing how important it is to ensure the vectors are appropriately sized for operations. The next operation uses the element-wise product (denoted with '.*'), which works correctly. You can see that the sum of these products yields a result, helping to illustrate vector computations.

Imagine you have two bags of apples and oranges. If you try to combine the bags without organizing them, you might drop some! This is similar to attempting an invalid multiplication of vectors. But once you pair them correctly — say, matching each apple to an orange — you can easily count how many fruits you have, just like summing the element-wise products of your vectors.

3 - Suppose that you are only interested in the commands defining vectors x and y, in the operations that produce the dot product of the vectors (i.e., sum(x.y) and xy'), and in the very last command (b = x*y' + y'x). Using the diary command create the file c:\myVectors.txt and collect only the commands of interest out of the command history buffer by using cntl-P and cntl-N as needed. The resulting SCILAB session should look like this: --> diary('c:\myVectors') -->x = [1, 2, 5, -4] x = ! 1. 2. 5. - 4. ! -->y = [0, 2, 3,-5] y = ! 0. 2. 3. - 5. ! -->sum(x.y) ans = 39. -->xy' ans = 39. -->b = xy' + y'*x b = ! 39. 39. 39. 39. ! ! 41. 43. 49. 31. ! ! 42. 45. 54. 27. ! ! 34. 29. 14. 59. ! -->diary(0)

Here, you learn how to selectively save important results from your SCILAB session into a text file. By using the diary command, you create a new file where only the relevant commands are saved. As a result, your output will clearly show commands that build up to your final important results, excluding any irrelevant or erroneous commands.

It’s like keeping a journal where you only write down the good days or important events. Instead of recording everything, you curate your experiences, ensuring what you keep is meaningful and relates to your journey.

This file can be edited or printed from a text editor such as NOTEPAD, or my favorite, PFE (Programmer’s File Editor) available for free from: http://www.lancs.ac.uk/people/cpaap/pfe.

Once you have your diary file, you may want to review or alter it for clarity or formatting. Using a text editor like NOTEPAD allows you to open the saved SCILAB session file and refine its contents. Text editors provide simple tools for making edits, adding comments, or beautifying the formatting, transforming raw code into a cleaner and more presentable format.

Think of it like writing a report. You first jot down your notes (like the output from SCILAB), but then you edit and format those notes to create a polished, formal document that looks professional and is easier to read.

SCILAB uses a current directory where files are saved by default, for example when using the function diary. To see the current directory use: -->pwd. Under a Windows operating system, the default current directory is typically c: . The command pwd stands for print working directory.

This chunk emphasizes the importance of organizing your SCILAB workspace through a current directory. By setting a specific directory, you can keep all relevant files and scripts together, ensuring an orderly environment for your calculations and results. You can check your current directory with the 'pwd' command, and create a dedicated workspace using the 'chdir' command.

Imagine setting up a dedicated study area at home where all your books and materials are neatly organized. This makes it easy to find what you need when studying (just like having your SCILAB files organized in a specific directory).

--