[otherguy]

Have you added debug print statements for you code to see if your inputs and outputs make sense?
THat might help you get a quick sanity check of where your code is going wrong.


Is there's a reason you don't want to do something a little simpler?

float joyx = stick->GetRawAxis(0);
float joyy = stick->GetRawAxis(1);
 
if(stick->GetRawButton(10)){
  multiplier = 0.4;
} else {
  multiplier = 1;
}
rBot->ArcadeDrive(joyy * multiplier, joyx * multiplier);

Just change your multiplier variable to affect commanded rate of travel.

It doesn't give you X^2 scaling, but not sure you need that.


Keeping the x^2 implementation:

float joyx = stick->GetRawAxis(0);
float joyy = stick->GetRawAxis(1);

//#nostarmaster
joyx = joyx * abs(joyx); 
joyy = joyy * abs(joyy);

if(stick->GetRawButton(10)){
  multiplier = 0.4;
} else {
  multiplier = 1;
}
rBot->ArcadeDrive(joyy * multiplier, joyx * multiplier);

I think this one does exactly what you were trying to do in your code.