HALFRAND
x = (int)((((double)(myrand()-HALFRAND)) *
((double)(myrand()-HALFRAND))/RANDRAND)
y = (int)((((double)(myrand()-HALFRAND)) *
((double)(myrand()-HALFRAND))/RANDRAND)
y = (int)((((double)(myrand()-HALFRAND)) *
((double)(myrand()-HALFRAND))/RANDRAND)
y = (int)((((double)(myrand()-HALFRAND)) *
((double)(myrand()-HALFRAND))/RANDRAND)