PI_2             1002 contrib/gregbook/rpng2-win.c                 angle = (x == 0)? PI_2 : atan((double)y / (double)x);
PI_2             1252 contrib/gregbook/rpng2-x.c                 angle = (x == 0)? PI_2 : atan((double)y / (double)x);
PI_2             2020 contrib/gregbook/rpng2-x.c                 angle = (x == 0)? PI_2 : atan((double)y / (double)x);