Dear All, I am not sure whether the following can be considered a bug: > x <- seq(-1,1,length=20) > y <- x > z <- matrix(1,20,20) > persp(x,y,z) Error in persp.default(x, y, z) : invalid 'z' limits It works with: persp(x,y,z,zlim=c(0,1.5)) Should not persp set the z limits by default when the matrix to draw is constant? Paul