this code is supposed to draw a line between two dots and tug them slightly towards each other, but for some reason the line "vx+=cos(a)*.01;" seems as though it's being run outside of the if() statement.  whenever I run the program all the dots accelerate to the right. switching it to "vx-=cos..." reverses the effect and changing "*.01" to "*0" nullifies it, but setting r to zero does not.  when I replace "vy+=sin..." with "vy+=cos..." the dots accelerate vertically. what's going on?

for(int j=0;j<dots.length;j++){
 if(dist(dots[j].x,dots[j].y,x,y)<=r){
   float a=atan2(dots[j].y-y,dots[j].x-x);
   vx+=cos(a)*.01;
   vy+=sin(a)*.01;
   stroke(255);
   line(dots[j].x,dots[j].y,x,y);
 }
}

oh! of course!
well I feel silly. thanks for your help.