I find a couple of places on the Internet that hint that there might be a software package named SPECTsingle, but I am not able to locate such a package, so I do not know what the code is that you are using.
The message is saying that SPECTsingle expected to be able to save one of its variables that it named infoC but that it was not able to do so, such as if the variable was not assigned to. infoC is nothing specific to MATLAB: it is some internal variable name for the package. For example, if you had code that looked like
for K = 1 : numimages
if mean(ImageData{K}(:)) > 0.3
infoC = K;
break
end
end
then you run the risk that the condition was never true and so infoC was never assigned to.
