# Example from bottom of page81 function rotate # point angle { nameref point=$1 float temp c=$((cos($2))) s=$((sin($2))) (( temp = c*point.x - s*point.y )) (( point.y = s*point.x + c*point.y )) (( point.x=temp )) } p=(x=1.0 y=0.0) rotate p $(( 2*atan(1.0) )) print p=$p