# Matlab program help

1. Mar 14, 2007

### kreil

1. The problem statement, all variables and given/known data
Write a matlab program to compute f'(0) for f(x)=e^x and h=1;0.1;0.01....1E-9 using the forward and central difference formula. What is the optimal h?

3. The attempt at a solution

I have no clue how to write programs in matlab, if anyone can help me get started I would REALLY appreciate it.

2. Mar 14, 2007

you mean a matlab script right?

3. Mar 14, 2007

Anyway my advice is to write a function as have h as the input, and f' as the output..
in the function, you will just write the formula as a function of h.
as for which value is optimum, well it's related to how close it is to the real value...

Last edited: Mar 14, 2007
4. Mar 14, 2007

### chroot

Staff Emeritus
Well, for staters, do you know the two expressions for the derivative that are mentioned in the assignment?

In other words, do you know how to express the derivative as each of these two kinds of differences?

- Warren

5. Mar 14, 2007

### kreil

no, i dont know what the formulas are

6. Mar 14, 2007

### chroot

Staff Emeritus
Then your first step must be looking up the definition of a derivative in your textbook.

- Warren

7. Mar 16, 2007

### kreil

i know what a derivative is, i dont know how to program in matlab.

$$f'(x)=\lim_{h{\rightarrow}0}\frac{f(x+h)-f(x)}{h}$$

8. Mar 16, 2007