ASCEND/C2/Iterative-calculations-and-Plotting-Graphs/English

Tutorial 6: Iteration & Graph Plotting

Visual Cue	Narration
Slide number 1 Title slide	Welcome to the tutorial on Iteration & Graph Plotting in ASCEND
Show Slide 2	In this tutorial, We will learn how to use FOR loop in ASCEND how to use Arrays in our MODEL and how to plot Graphs using ASCEND
Slide number 3 System Requirement	Here I am using Ubuntu Linux OS version 12.04 ASCEND version 0.9.8
Slide number 4 Pre-requisites	To follow this tutorial, user must have basic knowledge of Linux and ASCEND. To know more about ASCEND, please visit ascend4.org
Slide number 5 Problem Statement	This is the problem statement for this tutorial. Suppose we want to study the variation in mass of a thin walled cylindrical vessel with respect to its Height to Diameter ratio i.e. H to D ratio. The equation describing our system is the mass of the metal: metal mass = density of the metal into volume of the wall
Source Code in Text Editor	Let's look at the source code for this problem.
Zoom in on the MODEL vessel and paremeters part of the code.	We have two models in our file. The first model defines parameters that will be passed into second model. To know more on writing reusable models refer to other lectures in this series.
Zoom out and show the entire MODEL vessel	After defining the parameters, we define the required variables and equations. Then we write METHODs to solve them.
Zoom in on the second MODEL vesselplot.	Now we write our second MODEL vesselplot. This model uses the previously defined parameters.
Highlight the declaration of n_entries	We define the total number of data points that we want, by defining variable n_entries
Highlight the declaration of H_to_D_ratio and metal_mass	Therafter, we declare two arrays H_to_D_ratio and metal_mass.
Highlight the FOR loop	Now,we start a FOR loop, using which, we pass the parameters of previous model in a new array v.
Highlight the FOR loop in METHOD values	Note that,we assign values to the previously defined array H_to_D_ratio under METHOD values.
Open up ASCEND interface.Load the program and run it.	Before moving any further, let us load the ASCEND interface and then run our program.
On the ASCEND interface.	Let me open our file which is of the name vesselplot. Let me load the model.
On the ASCEND interface.	Let me run the values METHOD and solve it.
Point to the type 'array' displayed on interface	As you can see, ASCEND clearly indicates that H_to_D_ratio and metal_mass are of the type arrays.
Click on 'H_to_D_ratio' arrow	To see the different values stored in the array, we just click on the drop down menu. This shows all the values stored in the array H to D ratio.
Click on 'v' arrow	Also, to see the values of the various parameters passed to array v, we first click on the arrow next to it. Then we can click on the arrow next to any of these numbers to see the required values.
Source code in Text editor	Now, let's see how to plot graphs using ASCEND. Let me minimize this window and open the source code.
Highlight REQUIRE "plot.a4l”	Firstly, we need to include a new library in our MODEL'. The name of the library is plot.a4l
Highlight massVSratio IS_A plt_plot_symbol	To plot a graph in ASCEND, we need to declare a variable of the type plt_plot_symbol. Here we define mass v/s ratio as a variable of this type.
Highlight (CurveSet, Curves)	This declaration requires two parameters namely, Curveset and Curves.
Highlight the following lines: CurveSet IS_A set OF symbol_constant; CurveSet :== ['test'];	Curveset allows us to tag and identify each of the curves we plot.
Highlight the following lines: Curves['test'] IS_A plt_curve([1..n_entries], metal_mass,H_to_D_ratio)	The second parameter Curves requires 3 parameters- a set of integers two lists of data giving the y-values and the x-values for the curve. In our case, this set of integers is from 1 to 20. And the two arrays – metal_mass & H_to_D_ratio gives the y values and x values respectiveley.
Highlight the following lines: massVSratio.title :='Metal mass of the walls vs H to D ratio for a thin-walled cylindrical vessel'; massVSratio.XLabel := 'H to D ratio'; massVSratio.YLabel := 'metal mass IN kg/m^3	We give title and label for our plot under the METHODS section.
Open up ASCEND interface.Load the program and run it.	Let us now see how to get the required plot. Let us go back to the ASCEND interface.
Right-click on massVSratio and choose the plot option	Let us go to the variable mass vs ratio. Right-click on it and select the option plot.
Maximise the plot window	This gives us the required plot, with the title and the labels that we had mentioned in the code.
Source code in Text editor	Let us now see what happens if we don't mention the plot title.
Remove the massVSratio.tittle line from the source code and save it.	We remove the line that defines the title for our plot.
Open up ASCEND interface.Load the program and run it.	Let me save the file and reload it in the ASCEND interface. Let me again solve it and plot the graph again.
Maximise the plot window	We can clearly see that ASCEND titles the plot as 'Undefined'.
Slide number 6 Summary	This brings us to the end of this tutorial.
Click to bring up the bullets	In this tutorial, we have learnt How to use FOR loop in ASCEND How to use Arrays in our MODEL How to plot Graphs in ASCEND
Slide Number 7 Assignment	As an assignment to this tutorial, change the size of array to 40. And re-attempt this problem covered in this tutorial.
Slide Number 8 About slide	Information on the Spoken Tutorial project is available on the Internet.
Slide number 9 About slide	Workshops based on Spoken Tutorials are also available.
Slide number 10 Acknowledgment	Spoken Tutorial Project is funded by the NMEICT, MHRD.
Slide number 11 Thank you slide	This is Tarun Gangwar from IIT Bombay signing off. Thank you.

Contributors and Content Editors

Nancyvarkey, Tarung