MATLAB: Do I keep getting complex values from an if/else statement

if statementinequality

I'm trying to create values for a variable (called r2 in my code) using random numbers on [0,1] and an if/else statement. However, I keep getting complex values for r2 when that shouldn't happen. Is there an issue with the way I wrote my code? Here it is:
r = rand(25,1)
if r < 0.5
r2 = 0.5-sqrt(0.25-(r/2));
else
r2 = 0.5+sqrt((r/2)-0.25);
end

Best Answer

The problem is in the if block logic and the way MATLAB evaluates vectors. 
if r < 0.5
implies:
if all(r < 0.5)
that of course is not true, so the first section never evaluates.
You could put it in a loop, however this is more efficient: 
r2 = (0.5-sqrt(0.25-(r/2))).*(r<0.5) + (0.5+sqrt((r/2)-0.25)).*(r>=0.5);
.
Related Question