fixed relationship i have a line of code like this:

if ( (p/f==-1&&p<0&&f>0)||(p/f==1&&p>0&&f>0) ) {

s_mom2 = "When Object distance, u = f, use by spotlight when projecting parallel beam of light";
}


the rest of the times it seems p = -f =  0.4, 0.6 1.0, 1.4,1.6,2.0 works   it works for p/f==-1

but when p = -f = -0.2, -0.8, -1.2, -1.8, it fails.  It is very strange so i being thinking and thinking but i thought i bounce it off this forum!
thx!