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 Use Arrays in MODEL Plot Graphs
Slide number 3 System Requirement	Here I am using Ubuntu Linux OS v. 12.04 ASCEND v. 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 For relevant tutorials, please visit our website http://spoken-tutorial.org
Slide number 5 Problem Statement	Suppose we want to study the variation in mass of a thin walled cylindrical vessel with respect to its H to D ratio. The equations describing our system is: metal mass = metal density * wall vol
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 in the second model. To know more on writing reusable models refer to previous 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 to use 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 to store the required values.
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 and not in our MODEL.
Open up ASCEND interface.Load the program and run it.	Before moving any further, let's run our program and see how it stores the values in arrays.
Point to the type 'array' displayed on interface	As you can see, ASCEND clearly indicates that H_to_D_ratio, metal_mass and v are arrays.
Click on 'H_to_D_ratio' arrow	To see different values stored in the array, we just click on the drop down menu.
Click on 'v' arrow	Also, to see the values of the parameters passed to array v, we click on the arrow next to it.
Source code in Text editor	Now, let's learn how to plot a graph between the values stored in the two arrays.
Highlight REQUIRE "plot.a4l”	Firstly, we need to include plot.a4l library in our model to use the plot function.
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.
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 and two lists of data giving the y-values and the x-values for the curve. In our case, this set of integers is from 1to 20. And the two arrays – metal_mass & H_to_D_ratio gives the y 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.
Right-click on massVSratio and choose the plot option	We simply need to click on the mass vs ratio and choose the plot option.
Maximise the plot window	This gives us the required plot, with the title and the labels that we 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 title line from our source code.
Open up ASCEND interface.Load the program and run it.	We will re-compile the program.
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. Let’s summarize.
Click to bring up the bullets	In this tutorial, we have learnt to Use FOR loop in ASCEND Use Arrays in MODEL Plot Graphs using a sample program
Slide Number 7 Assignment	As an assignment, change the size of array to 40 and re-attempt this problem.
Slide Number 8 About slide	Watch the video available at http://spoken-tutorial.org/What_is_a_Spoken_Tutorial It summarises the Spoken Tutorial project If you do not have good bandwidth, you can download and watch it
Slide number 9 About slide	The Spoken Tutorial Project Team: Conducts workshops using spoken tutorials Gives certificates to those who pass an online test For more details, please write to contact@spoken-tutorial.org
Slide number 10 Acknowledgment	Spoken Tutorial Project is a part of the Talk to a Teacher project It is supported by the National Mission on Education through ICT, MHRD, Government of India More information on this Mission is available at[1]http://spoken-tutorial.org/NMEICT-Intro
Slide number 11 Thank you slide	This is Tarun Gangwar from IIT Bombay signing off. Thank you for joining.

Contributors and Content Editors

Nancyvarkey, Tarung