How to add Latex formatted text in a Scilab plot

Latex makes possible to write equations in a mathematical format, by using all the symbols and characters specific to mathematics language. Scilab allows the usage of Latex formatted text, in the plot related functions, such as: xlabel(), ylabel(), title(), legend() and xstring().

In order to input Latex instructions, for any of the Scilab plot related functions, the user has to use the dollar $ sign. This is placed in the string argument of the function, at the beginning and the end of the string. For example, in order to input the Greek character α as the x-axis label, we need to write:

xlabel('$\alpha$')

Let’s take as example two random functions f1(α) and f2(α), defined as:

\[ \begin{equation*} \begin{split}
f_1(\alpha)=sin(\alpha)-\frac{1}{1+\sqrt{\alpha}}\\
f_2(\alpha)=cos(\alpha)+\frac{1}{1+\sqrt{\alpha}}
\end{split} \end{equation*} \]

The Scilab instructions below generates a vector for the angle α between 0 and . The functions are then evaluated for all values of α. Both functions are plotted function of the value of the angle.

alpha = [0:0.01:2*%pi];
f1=sin(alpha)-1 ./(1+sqrt(alpha));
f2=cos(alpha)+1 ./(1+sqrt(alpha));
plot(alpha, f1)
plot(alpha, f2, 'r')
xgrid
xlabel('$\alpha \quad [\text{rad}]$','fontsize',4)
ylabel('$f(\alpha)$','fontsize',4)
legend('$\Large{f_1(\alpha)}$','$\Large{f_2(\alpha)}$',1)
title(['Plot of the functions ' '$f_1(\alpha)$' ' and ' '$f_2(\alpha)$'],'fontsize',3)
xstring(1,1,'$\LARGE{sin(\alpha) - \frac{1}{1+\sqrt{\alpha}}}$')
xstring(0.15,-1.15,'$\LARGE{cos(\alpha) + \frac{1}{1+\sqrt{\alpha}}}$')

By running the above Scilab instructions in a script file (*.sce), we’ll get the following graphical window:

Scilab plot with Latex formatted text

Image: Scilab plot with Latex formatted text

As you can see, we’ve used Latex instructions for all text annotations functions of the plot: xlabel(), ylabel(), legend(), title() and xstring().

We can combine normal text with Latex text by entering them as a vector of strings. This technique can be seen in the title() function, with the string vector:

['Plot of the functions ' '$f_1(\alpha)$' ' and ' '$f_2(\alpha)$']

The xstring() function allows the user to place any text in the graphical window, by specifying the x, y coordinates and the text to be displayed.

Scilab allows to usage of Latex syntax in all the plot related string functions. With this feature, the user can format the images to display complex mathematical equations together with the line plot.

For any questions or observations regarding this tutorial please use the comment form below.

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