New empty figure window shows up every time I run this colormap command

I have a program created using App-Designer.

After adding the code below to my script, it would generate a new empty figure, every time I run the program.

colormap(app.Plot15, redwhiteblue(-40, 40));

https://www.mathworks.com/matlabcentral/fileexchange/86932-red-white-blue-colormap

What did I do wrong?

Answer 1

[Stephen23]

"What did I do wrong?"

The documentation you referenced clearly states it's behavior with two input arguments: "REDWHITEBLUE(VMIN,VMAX), by itself, is the same length as the current figure's colormap. If no figure exists, MATLAB creates one."

If you are using a UIFIGURE (with it's default hidden handle) OR there is no figure open then I would expect a new figure to open, just as it's documentation explains.

we can also see in the code that with two arguments GCF is called: what do you expect to happen when GCF is called?

[Leon]

Many thanks for the tips.

In that case, how do I specify different colormaps for different plots then? I have many separate plots in my program.

[Stephen23]

"how do I specify different colormaps for different plots then?"

Provide REDWHITEBLUE's third input argument.