1.4.4 - Selective worksheet output
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Understanding Command History
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Today, we're going to talk about command history in SCILAB. Can anyone tell me why recording commands is useful?
It helps keep track of what we've done during the session for later reference!
Exactly! It's crucial for documentation and understanding our progress. Remember, SCILAB saves every command we enter, which can be managed using the `diary` command.
How do we use that `diary` command?
Great question! You start by typing `diary('filename.txt')` to begin recording. Does that make sense?
Yes! And when do we stop recording?
You can stop by typing `diary(0)`. This will help you create clean documentation of your relevant commands.
So, let's remember, `diary` for recording, and when you're ready to stop, use `diary(0)`. Can anyone summarize what we learned about `diary`?
We use `diary` to record commands in SCILAB into a file and stop it with `diary(0)`!
Applying Selective Output
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Now that we understand `diary`, let's discuss selective output. What does that mean?
It means only keeping the useful commands and results we care about.
Right! For instance, if you perform multiple operations on vectors, how would you focus only on significant commands?
We could use `Ctrl-P` and `Ctrl-N` to navigate through the command history.
Exactly! That allows us to select which commands are worth saving. Can anyone give an example?
If I computed the dot product of two vectors, I'd want to keep those lines and ignore the errors.
Very good! Always aim to filter out unnecessary data. What did we learn today? Can someone summarize?
We learned to use `Ctrl-P` and `Ctrl-N` to filter significant commands from our SCILAB session!
Practical Exercise on Selective Output
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Let's put our knowledge to the test! How do we start a SCILAB session with our vectors?
We could define our vectors like `x = [1, 2, 5, -4]` and `y = [0, 2, 3, -5]`.
Perfect! Now, after running several operations, how do we document just the useful commands?
Use the `diary` command to start saving, and after filtering with `Ctrl-P` and `Ctrl-N`, we'll save relevant lines.
Yes! And remember, it’s about efficiency and focus. We want only what matters. Who wants to try summarizing the commands we need to keep?
Keep the commands like `sum(x.*y)` and the results, and discard errors.
Exactly! Selectivity helps us master our learning. Anyone else? Can summarize the three main points?
Use `diary` to start recording, filter with `Ctrl-P` and `Ctrl-N`, and keep only the valuable outputs!
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
The content explains how to use SCILAB's command history to filter and document specific commands that contribute to the desired outputs. It emphasizes the importance of capturing only the relevant results while learning vector operations.
Detailed
Detailed Summary
This section focuses on how to selectively document SCILAB command outputs that are relevant to a user's needs. In lengthy sessions, users may encounter numerous commands, some of which yield errors or irrelevant intermediate results. To aid in effective learning and review, students can utilize SCILAB's command history features to filter their output. A detailed example demonstrates vector operations using the vectors x and y, where the user captures only the commands and results that contribute to meaningful outputs, while maintaining a structured documentation process with the diary command. This selective output method ensures that learners focus on critical insights and avoids cluttering their review notes or documentation.
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Introduction to Selective Output
Chapter 1 of 5
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Chapter Content
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.
Detailed Explanation
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.
Examples & Analogies
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.
Basic Example of Vector Operations
Chapter 2 of 5
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Chapter Content
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. !
-->xy
!--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. !
Detailed Explanation
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.
Examples & Analogies
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.
Filtered Command History
Chapter 3 of 5
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Chapter Content
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 = xy' + 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)
Detailed Explanation
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.
Examples & Analogies
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.
Using a Text Editor with SCILAB
Chapter 4 of 5
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Chapter Content
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.
Detailed Explanation
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.
Examples & Analogies
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.
Creating a Work Directory
Chapter 5 of 5
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Chapter Content
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.
Detailed Explanation
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.
Examples & Analogies
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).
Key Concepts
-
Selective Output: The practice of filtering out unnecessary commands and saving only important results.
-
Command History: A feature in SCILAB to revisit entered commands.
-
Diary Command: A command to record the session’s commands in a specified file.
Examples & Applications
Using diary('session.txt'), you can capture all SCILAB inputs during a session.
To discard irrelevant outputs, navigate using Ctrl-P and Ctrl-N to select significant commands.
Memory Aids
Interactive tools to help you remember key concepts
Rhymes
Diary helps you save your way, keep the good, and throw the gray!
Stories
Imagine a student named Sam who always forgets commands. He uses his diary to write only the important ones, ensuring he captures the essence without the errors.
Memory Tools
D for Diary, C for Clean - Remember to filter out what's unseen!
Acronyms
S.O.L.D (Selective Output, Log Diary) - Always save what’s essential.
Flash Cards
Glossary
- Diary Command
A SCILAB command that allows users to record all input and output from a session to a text file.
- Vector Operations
Mathematical operations that can be performed on vectors, like addition and dot product.
- Command History
A feature in SCILAB that keeps a record of all commands entered during a session.
Reference links
Supplementary resources to enhance your learning experience.