sprintf with latex problem

I just cannot figure out what the problem is with this line, please help. I get this warning sometimes:

Warning: Error updating Text.

   Character vector must have valid interpreter syntax:
  $ρ_t = 0.26ρ_f, θ_0 = 90°$

Regardless, the subscripts never take. Here is the problematic line:

title(sprintf('$%c_t=%.2f%c_f,%c_0=%2.0f%c$',961,idens,961,952,iang*180/pi,176),'Interpreter','latex');

Answer 1

[Walter Roberson]

latex cannot have any characters with position greater than 255. That is violated by your 961 (rho) and 952 (theta).

Use \rho and \theta

https://www.mathworks.com/matlabcentral/answers/14751-greek-alphabet-and-latex-commands-not-a-question

[xtremecheez]

I was not aware of that, but this doesn't quite work either:

title(sprintf('$\rho_t = %.2f\rho_f, \theta_0 = %2.0f%c$',idens,iang*180/pi,176),'interpreter','latex');

nor this with \\greek instead of \greek:

title(sprintf('$\\rho_t = %.2f\\rho_f, \\theta_0 = %2.0f%c$',idens,iang*180/pi,176),'interpreter','latex');

For both I get the following warning:

Character vector must have valid interpreter syntax:
$\rho_t = 0.26\rho_f, \theta_0 = 90°$

[Walter Roberson]

The degree character is causing the problem. Use ^{\circ}

[xtremecheez]

That was it, thanks.

Answer 2

[Amirali Kamalian]

I have a problem quite similar to this:

pltt = '%1.0u: %4u $^{\circ}$C, %4u kg/h';
...
title(sprintf(pltt, j, T, Q),'FontSize', 12,'Interpreter','latex')

When executing this code, I get the following warning:

"String scalar or character vector must have valid interpreter syntax". Furthermore,

"Warning: Escaped character '\c' is not valid."

Any ideas how to fix this?

[Stephen23]

You forgot to escape the backslash, i.e. \\circ instead of \circ. This is because you are supplying pltt as the format string to sprintf, so any special characters in it that you want to be treated as literal characters will need to be escaped: you should always check the output of sprintf before using it.

[Amirali Kamalian]

Thanks Stephen!