[R] Copula in R 2.4.0

[Dominique Katshunga]

Dear R helper,
does anyone have an idea on why R.2.4.0 draws the surface for the two
command lines below and the next time it renders the error message below
for exactly the same command lines:

> norm.cop <- normalCopula(0.5)
> persp(norm.cop, dcopula)

Error in ceiling(length.out) : Non-numeric argument to mathematical
function.
I will appreciate any help from anyone
thanks,
Dominique K.