Is it possible to display a multiplication operator in symbolic math's displayFormula output?

I am using the Symbolic Math Toolbox's function displayFormula() in Live Editor to display a series of equations and subsequent answers. When I try and show intermediate steps, filling the equations with the actual values found, where there would be a multiplication symbol (∗), it just outputs blank space. This works for variables where a*b displays , but with numbers 1*1 it displays as , which looks like eleven.

The code I'm working with:

syms x1 x2 x3 N1 N2 N3 s t N_i

dNs = "diff(N_i(s,t),s)";  % dN as a string for display

N1(s,t) = 1-s-t; % Shape functions
N2(s,t) = s;
N3(s,t) = t;

dN1s = diff(N1,s);  % Calc partial derivatives
dN2s = diff(N2,s);
dN3s = diff(N3,s);

x1 = 0; % set x coords
x2 = 1;
x3 = 0;

sumdNsx = dN1s*x1+dN2s*x2+dN3s*x3;

displayFormula("symsum(dNs*x_i,i,1,3)==dN1s*x1+dN2s*x2+dN3s*x3==sumdNsx")

Output:

Should be something like:

or

* Side note: Wouldn't mind getting rid of the parentheses too.

Answer 1

[Sai Sumanth Korthiwada]

Hi Tim,

As of Symbolic Math Toolbox R2022b, multiplication symbol (*) outputs a blank space for integers as well. Because the input given to the function gets evaluated. As a workaround, you can use

"'*'" % use this to add a '*' in between the formula

Also, pass a cell array of character vectors [ ] rather than passing a string, if you want to use '*' symbols in the formula.

syms x1 x2 x3 N1 N2 N3 s t N_i
dNs = "diff(N_i(s,t),s)";  % dN as a string for display
N1(s,t) = 1-s-t; % Shape functions
N2(s,t) = s;
N3(s,t) = t;
dN1s = diff(N1,s);  % Calc partial derivatives
dN2s = diff(N2,s);
dN3s = diff(N3,s);
x1 = 0; % set x coords
x2 = 1;
x3 = 0;
sumdNsx = dN1s*x1+dN2s*x2+dN3s*x3;
% displayFormula("symsum(dNs*x_i,i,1,3)==dN1s*x1+dN2s*x2+dN3s*x3==sumdNsx")
%% instead try:
% to use '*' in the formula, workaround:
displayFormula(["symsum(dNs*x_i,i,1,3)==dN1s","'* '","x1+dN2s","'* '","x2+dN3s","'* '","x3==sumdNsx"])
% to use '(' in the formula, workaround:
displayFormula(["symsum(dNs*x_i,i,1,3)==dN1s","'('","x1","')+'","dN2s","'('","x2","')+'","dN3s","'('","x3","')='","sumdNsx"])

Hope this helps!

[Tim]

That works, thank you!

I do think when displaying integers symbolically, there should be a caveat in the program to display the operator, otherwise it displays incorrectly. But this work around does the trick for now. I will likely have to build a simple function to replace the * operators with a symbol so it can be applied repeatedly.

Appreciate you taking the time to answer my question. Cheers