On Jan 19, 3:02 pm, tome...@gmail.c om wrote:

Hi,

I had to write a class which would emulate FPU using normal fixed point

operations, and to test it in some real application. I thought about

some encoding programs but I don't have much idea, which one would be

suitable. I mean that 1. it would use FPU a lot - to be able to see

some difference in time, 2. it would be relatively easy to change the

source code to accept my class (which is written in C++). If you've got

any idea, please help, I would really appreciate it.

It might be of interest to compare different kinds of operations, for

example + and - are usually quite fast (talking float/double here)

while * and / can take some time. So perhaps you can start of by

creating some synthetic benchmarks, use some random routine to produce

a list of say 1000 FP numbers, for each of them create a double version

and a yourtype version and put them in an array. Then comes the

benchmark: first measure the time it takes to perform some operation

(summing) the doubles then measure the time needed to do the same

operation on your types.

If you want more realistic benchmarks try finding an algorithm for

solving systems of linear equations and implement it. Use a typedef for

the type used in the calculations so you can easily switch (given that

yourtype have similar interface as float/double) and then download a

matrix from the next and try to solve the system (it's a O(n^3)

operation for simple algorithms). I'd recommend a matrix of size

somewhere between 500x500 to 5000x5000, it's better to run the test

many times than taking a too large matrix.

--

Erik Wikström