Gnuplot/C2/Plotting-functions/English
| Visual Cue | Narration |
| Slide Number 1
Title Slide Plotting functions |
Welcome to the tutorial on Plotting functions |
| Slide Number 2
Learning Objectives |
In this tutorial we will learn,
|
| Slide Number 3
Learning Objectives |
|
| Slide Number 4
System and Software Requirement |
To record this tutorial, I am using
|
| Slide Number 5
Pre-requisites |
To follow this tutorial, learners must be familiar with,
and
|
| Ctrl alt t | Open a terminal by pressing control alt t keys together
A terminal opens |
| >gnuplot. | Enter command gnuplot, to open gnuplot |
| control shift k | The terminal prompt changes to gnuplot when program runs
I will clear the screen and bring terminal prompt to top of the screen for clarity. |
| >plot sin (x) and press enter | Type, plot space sin x
Note that angle X is within braces and press enter |
| A graphical window with plot of x, sin x appear on screen | |
| Hover mouse on graph, axes | Limit of y axis is from -1 to plus 1 and x axis is from -10 to 10 |
| Click on grid icon | Click on the grid icon. This draws grid in the graph. |
| Hold control and zoom in with mouse scroll | Hold down control key and zoom in around origin, 0, 0, with scroll mouse |
| Notice, sin x is zero when x is zero | |
| Show zoom in and out | Using scroll wheel, zoom in and out in the graph. |
| Type reset, enter
Type replot, enter |
To reset, enter command reset in terminal, followed by replot
Changes in graph becomes visible only after replot command |
| This resets limits of axis as before | |
| Notice the legend in the graph is not clear and runs through the graph | |
| Point mouse on legend | Let's increase y-axis range, so that graph line does not run through legend. |
| >set yrange [-2:2] | Enter command set space yrange space -2 colon 2 within square braces |
| >set xrange [-20:20] | Change x-range with command set space xrange space -20 colon 20 in square braces |
| replot | Enter replot command to see the updated graph. |
| Now the changed graph limits are visible. | |
| Legend has moved upward and does not run through the data line. | |
| >set key top left | Command set space key space top space left will move legend to top left side. |
| >replot | Do not forget to replot to see the result. |
| Next, let's make the axis fonts larger.
I want to set them at size 14 and in Verdana style, a bit larger than present | |
| >set tics font “Verdana, 14”
>replot |
Enter command set space tics space font space Verdana comma 14 in double quotes
Replot to see the result. |
| Notice the larger font size in Verdana style. | |
| set xlabel 'x (angle)' font ‘Verdna, 14’ | Let's set x axis label as x angle next.
Please follow the commands as seen in the video Here we are specifying the font style and size in the same command line |
| set ylabel 'sin (x)' font ‘Verdana, 14’ | To set y-axis label as sin x, type command, as seen in the video |
| I will set the same font style and size for y axis too.
Changes in graph will become visible only after replot command. | |
| >replot | Hence type replot and enter. |
| Type set key font ",14" | Set space key space font space comma 14 in double quotes command sets font size to 14. |
| Type help fonts | To access help documentation on fonts, type help space fonts |
| Point mouse to cairo, gd and postscript | Help command returns with 3 subtopics cairo, gd and postscript |
| >cairo | I will type cairo to see the details and available options
You may pause the video, read & understand the details given in the help section |
| ctrl c
ctrl l |
Similarly you may choose to use help for any command when using gnuplot.
Press control c to exit help section I will clear the screen and bring prompt to top of the screen for clarity. |
| >set title 'My first gnuplot' | I will also add a title, reading, my first gnuplot.
To add title, enter command, set space title as seen in the video |
| >set title font ‘verdana, 18’
replot |
To set title font, use the command as seen.
Enter replot command to see the updated graph |
| Note that, x axis has dimensions of angle this plot
Hence we may like to label x-axis, in terms of angle, pi | |
| Point at the terminal
Highlight the following command and hover mouse over {/symbol p} and -2*pi set xtics ('-4{/Symbol p}' -4*pi,'-3{/Symbol p}' -3*pi,'-2{/Symbol p}' -2*pi, '-{/Symbol p}' -pi, 0, '{/Symbol p}' pi,'2{/Symbol p}' 2*pi, '3{/Symbol p}' 3*pi, '4{/Symbol p}' 4*pi,) |
To change xtics to angle, type the following command as seen on screen
Here we are setting Greek pi alphabet and set it's position. |
| Point mouse to ('-2{/Symbol p}' and then to -2*pi | This command placed label 2 pi at position 6.28 at x-axis. |
| replot | X-tics is labeled, Greek symbol pi is placed at value of 3.14
Enter replot command to see the updated graph |
| Type help set xtics
ctrl-c |
For more help on formats, enter command, help space set space xtics.
Pause the video and explore more if you wish to do so. |
| ctrl c | Press control c to exit help
It is also possible to add multiple functions on the same graph |
| To plot sin x and cos x on same graph, separate the functions by a comma | |
| plot sin (x), cos (x) | Enter command, Plot space sin x comma cos x
Make sure, the angle x, is typed within braces Notice the two functions plotted together |
| Next, add sin x plus cos x function to the graph | |
| plot sin(x), cos(x), sin(x) + cos(x) | For this, type plot space sin x comma cos x comma sin x plus cos x
Notice the three functions plotted together |
| Say, next I want to get sin x data points in a file | |
| set table | To get an ascii column format output, set table command can be used
First enter command set space table |
| plot sin(x) | Type, plot space sinx
An x y column data for sin x is generated on the screen |
| x y column data is generated on the screen | First column is x data and second column is y data points of x sinx graph |
| Clear screen , ctrl shift k | We can pipe or 'direct' the output to a text file.
I will clear the screen and bring prompt to top of the screen for clarity. |
| >set table "table-sinx.txt" | For this, type, set space table space in double quotes table hyphen sinx dot txt |
| plot sin(x) | Type plot space sin x
Here, the output is directed to file name table hyphen sin x dot txt |
| The file is stored in the directory from where we opened gnuplot in terminal.
We can remove tabular outputs with unset table command | |
| >unset table | Enter command unset space table to unset table mode |
| Slide Number 6
Summary |
To summarize, in this tutorial, we
Learned to
and
|
| Slide Number 7
Assignment |
For assignment, plot the following functions,
and
|
| Slide Number 8
Spoken Tutorial Project |
This video summarises the Spoken Tutorial Project
Please download and watch it. |
| Slide Number 9
Spoken Tutorial workshops |
We conduct workshops and give certificates.
Please write to us. |
| Slide Number 10
Forum for specific questions: |
Post your timed queries in the forum. |
| Slide Number 11
Acknowledgement’’’ |
Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India. |
| This is Rani from IIT, Bombay. Thank you for joining. |
