(require (lib "plot.ss" "plot"))

(define (trig x y) (* (sin x) (sin y)))

(plot (vector-field (gradient trig) '((samples 25)))
      (x-min -1.5) (x-max 1.5) (y-min -1.5) (y-max 1.5) 
      (title "gradient field of F(x,y) = sin(x) * sin(y)"))