Derivative of a function

**krusader23** · 11-28-2009, 11:36 PM

Hi,
is there a way to calculate a derivative of a function?
For example I have this function in one cell: f(x)=x^2 and I want excel to automatically convert that function to the derivative (f'(x)=2x). It would also be nice, if there was a function, which could substitute a given value as "x" in the function formula and calculate the "y".

Functions like:
double derivative(char* function, char c, double value)
double calcFunction(char* function, char c, double value)

My Casio Algebra 2.0+ can calculate the derivatives in this way (using the CAS system).

Cheers.

**shg** · 11-29-2009, 12:18 AM

You can name a cell x, enter a value, and then enter a formula that uses x, e.g., =x^2 + 2*x - 1

As to calculating derivatives -- Excel doesn't do symbolic algebra.

**krusader23** · 11-29-2009, 09:24 AM

Maybe somebody know of the external (free) VBA libraries to deal with the problem?

//Edit: I found a way to do it. There is a matlab (a mathematical program) extension that lets you integrate the matlab functions with excel. (Matlab functions will work as the excel macros).
But I haven't tested it, because I haven't got the time to read through all the matlab documentation. So if someone ever tries this solution, please post your assesment on it.

**mrsmirf** · 09-30-2013, 08:34 AM

I was recently searching for a way to to this, and then it hit me. Excel has matrix function like matrix multiplication etc. well you can find the derivative of a function by taking it in the form of a matrix and multiplying it by the derivative. for instance, a 3x1 matrix (broken into terms) from y= x^3+x^2+x would become y=3x^2+2x+1 when multiplied by [0,1,0;0,2,0;0,0,3]. This maybe one of the easiest ways excel offers. I am on the search for an easier way though. Let me know if an example is needed.

**arlu1201** · 10-01-2013, 02:06 AM

mrsmirf,

Unfortunately you need to post your question in a new thread, it's against the forum rules to post a question in the thread of another user. If you create your own thread, any advice will be tailored to your situation so you should include a description of what you've done and are trying to do. Also, if you feel that this thread is particularly relevant to what you are trying to do, you can surely include a link to it in your new thread.