Taking the derivative of a long function

I have written out a function and I need to take the derivative of that function. However, when I try to use diff() I am getting an error. The method I am trying to use is below.

func = @(x) (1/sqrt(x))+2.0*log10(((n/d)/3.7)+(2.51/(re*sqrt(x))));
dfunc = diff(func);

It is worth noting that the only variable is x. All the other variables have been inputted by the user.

Answer 1

[Walter Roberson]

diff() has two major forms. One of the forms requires that the first input is numeric, in which case it calculates numeric differences, x(2:end)-x(1:end-1)

The other form requires that the first parameter is a symbolic expression or symbolic function. This is the derivative form.

You are trying to pass a function handle to diff. No diff() is defined for that.

Unless you use the symbolic toolbox, you can can only take numeric derivatives (except for some specially constructed forms such as spline or polynomials)

[Raymond Elliott]

Thats what I assumed. Thank you for the timely response!