Ive been trying to write a program to calculate the radius of curvature for a fuction in terms of x at a specific value of x. What I want to do is put the function on level two and the value for x on level one and then execute.

fX '((1+f'X)^3/2)/f''X 'EVAL EVAL EVAL

This works but only if Ive got the X value stored as a VAR. I dont want that.

I want to do it all in one step without extra variables in the directory or calling another program.

X fX 'rad(X)=((1+f'X... is what Im trying to do but I cant find anything that deals with this. Im not sure if it can even be done. Any help would be appreciated. Oh yea, is there any other way of taking a second derivitive of fx without parenthasizing it twice? Tod Lewis

Tod,

Please see my response sent in e-mail. This board unfortunately doesn't allow the use of characters like greater-than or less-than, making it very difficult to post User RPL solutions.

Viktor