Processing 'It looks like you're mixing "active" and "static" modes.' - comments

Question

Processing keeps giving me this error when I run it even though it is just a print command. When I delete the comment block it works fine. Here's the code:
/*
float[] cortToPolar(int xcorr, int ycorr) {
float returns[] = new float[2];
returns[0]= degrees(tan(ycorr/xcorr));
returns[1]= sqrt(pow(xcorr,2)+pow(ycorr,2));
return returns;
}
float lawCos(int a, int b, int c) {
return degrees(
acos(
(pow(a,2)+pow(b,2)-pow(c,2))/
(2*a*b)
)
);
}
*/
print(0);
Why doesn't it like my comment?

Answer 1

Processing runs in two separate modes: static or active
Static mode simply means it's a list of instructions/calls to existing functions (e.g. draw a bunch of lines then exit)
Active mode uses the setup() and draw() calls and runs continuously (gets updated every 'frame').
Only in active mode you are allowed to define own functions like cortToPolar and lawCos (regardless of the fact they are commented - this could be a Processing editor bug).
Use the setup() call to print because using setup will bring Processing into active mode.
/*
float[] cortToPolar(int xcorr, int ycorr) {
float returns[] = new float[2];
returns[0]= degrees(tan(ycorr/xcorr));
returns[1]= sqrt(pow(xcorr,2)+pow(ycorr,2));
return returns;
}
float lawCos(int a, int b, int c) {
return degrees(
acos(
(pow(a,2)+pow(b,2)-pow(c,2))/
(2*a*b)
)
);
}
*/
void setup(){
print(0);
}
(Should you need to use active mode and control how draw() is called you can use noLoop() and loop().)

Answer 2

The message could be shown when the actual problem is a syntax error. I encountered this error with the following (silly) code:
boolean state = false;
setup() {
size(200, 800);
}
void draw() {
}
It is missing the 'void' modifier for the setup function. This is a syntax error (at least, it should be). But the Processing IDE gives you this "active vs. static" message instead.
So in this case, it should be void setup() { } rather than just setup() { }.