Python/C2/Using-sage-to-teach/English

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Visual Cue Narration
Show Slide 1

Containing title, name of the production team along with the logo of MHRD

Hello friends and welcome to the tutorial on 'Using SAGE to teach'.
Show Slide 2

Learning objectives

At the end of this tutorial, you will be able to,
  1. Use @interact feature of SAGE for better demonstration.
  2. Share, publish and edit SAGE worksheets for collaborative learning.


Show Slide 3

Pre-requisite slide

Before beginning this tutorial,we would suggest you to complete the tutorial on "Getting started with Sage" and "Getting started with Symbolics."
Open sage notebook
t = var('t')
p1 = plot( e^(-t) * sin(2*t), (t, 0, 15))
show(p1)
Let us start by looking at a typical example of demonstrating a damped oscillation.
t = var('t')
p1 = plot(e^(-t/2) * sin(2*t), (t, 0, 15))
show(p1)
Now let us reduce the damping factor by half
@interact
def plot_damped(n=1):
    t = var('t')
    p1 = plot( e^(-t/n) * sin(2*t), (t, 0, 20))
    show(p1)
Now if we want to reduce the damping factor even more, we would be using e^(-t/3). We can observe that every time we have to change, all we do is change something very small and re-evaluate the cell.

This process can be simplified, using the @interact feature of SAGE.

2<enter> We can see that the function is evaluated and the plot is shown. We can also see that there is a field to enter the value of n and it is currently set to 1. Let us change it to 2 and hit enter.
We see that the new plot with reduced damping factor is shown. Similarly we can change n to any desired value and hit enter and the function will be evaluated.

This is a very handy tool while demonstrating or teaching.

Pause the video here, try out the following exercise and resume the video.

Show Slide 4

Assignment 1

Plot the sine curve and vary its frequency using the @interact

feature.

Continue from paused state Switch to the sage worksheet
@interact
def sine_plot(n=1):
    x = var('x')
    p2 = plot(sin(n*x), (x, 0, 2*pi))
    show(p2)
Switch to your worksheet for solution.
@interact
def plot_damped(n=(1..10)):
    t = var('t')
    p1 = plot( e^(-t/n) * sin(2*t), (t, 0, 20))
    show(p1)
Often we would want to vary a parameter over range instead of taking it as an input from the user. For instance we do not want the user to give n as 0 for the damping oscillation we discussed. In such cases we use a range of values as the default argument.
We get similar plot but the only difference is the input widget. Here it is a slider unlike an input field.
Move the slider two times and show the plot obtained We can see that as the slider is moved, the function is evaluated and plotted accordingly.

Pause the video here, try out the following exercise and resume the video.

Show Slide 5

Assignment 2

Take a string as input from user and circular shift it to the left and

vary the shift length using a slider.

Continue from paused state Switch to the sage worksheet
@interact
def str_shift(s="MADAM", shift=(0..8)):
    shift_len = shift % len(s)
    chars = list(s)
    shifted_chars = chars[shift_len:] + chars[:shift_len]
    print "Actual String:", s
    print "Shifted String:", "".join(shifted_chars)
For this problem, again we will use the @interact feature of sage. We shall first assign a string say 'MADAM' to a variable and then shift the alphabets one by one.
Move the slider 2 times and show the output As we move the slider, we see that shifting is taking place.
@interact
def str_shift(s="STRING", shift=(0..8), direction=["Left", "Right"]):
    shift_len = shift % len(s)
    chars = list(s)
    if direction == "Right":
        shifted_chars = chars[-shift_len:] + chars[:-shift_len]
    else:
        shifted_chars = chars[shift_len:] + chars[:shift_len]
    print "Actual String:", s
    print "Shifted String:", "".join(shifted_chars)
Sometimes we want the user to have only a given set of options. We use a list of items as the default argument in such situations.
We can see that buttons are displayed which enables us to select from a given set of options.
Demonstrate the use of left and right buttons press 'left' button and move the slider to show the output

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then press 'right' button and move the slider to show the output

We see that, as we select the left or right button, the shifting takes place appropriately.

Thus, we have learnt how to use the @interact feature of SAGE for better demonstration. Now we shall look at how to use SAGE worksheets for collaborative learning.

Open a new worksheet and click on the 'publish' button The first feature we shall see is the publish feature. Open a worksheet and in the top right, we can see a button called publish. Click on that and we get a confirmation page with an option for re-publishing.
Demonstrate the actions For now lets forget that option and simply publish by clicking yes. The worksheet is now published.

Now lets sign out and go to the sage notebook home. We see link to browse published worksheets. Lets click on it and we can see the worksheet. This does not require login and anyone can view the worksheet.

Alternatively, if one wants to edit the sheet, there is a link on top left corner that enables the user to download a copy of the sheet onto their home. This way they can edit a copy of the worksheet.

We have learnt how to publish the worksheets to enable users to edit a copy.Next, we shall look at how to enable users to edit the actual worksheet itself.

Open a worksheet Let us open the worksheet and we see a link called share on the top right corner of the worksheet. Click the link and we get a box where we can type the usernames of users whom we want to share the worksheet with. We can even specify multiple users by separating their names using commas. Once we have shared the worksheet, the worksheet appears on the home of shared users.
Show Slide 6

Summary slide

This brings us to the end of this tutorial.In this tutorial, we have learnt to,
  1. Use interactive features of SAGE using @interact.
  2. Publish our work.
  3. Edit a copy of one of the published worksheets.
  4. Share the worksheets with fellow users.


Show Slide 7

Self assessment questions slide

Here are some self assessment questions for you to solve
  1. Which default argument, when used with @interact gives a slider starting at 0 and ending in 10.
    • (0..11)
    • range(0, 11)
    • [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    • (0..10)
  1. What is the input widget resulted by using n = [2, 4, 5, 9] in

Enumerated list ends without a blank line; unexpected unindent.

the default arguments along with @interact.

  • input field
  • set of buttons
  • slider
  • None


Show Slide 8

Solution of self assessment questions on slide

And the answers,
  1. The default argument, used with @interact which gives a slider starting at 0 and ending in 10 is (0..10).
  2. The input widget resulted by using n = [2, 4, 5, 9] in the default arguments along with @interact will be a set of buttons.


Show Slide 9

Acknowledgment slide

Hope you have enjoyed this tutorial and found it useful. Thank you!

Contributors and Content Editors

Chandrika