flops

This is really taking my time. I could not find a simple way to estimate FLOPS for a following code (the loop), How much FLOPS are for a single iteration of the loop: float func(float * atominfo, float energygridItem, int xindex, int yindex) { ... for (atomid=0; atomid<numatoms*4; atomid+=4) { float dy = coory - atominfo[atomid+2]; float dysqpdzsq = (dy * dy) + atominfo[atomid+3]; float dx1 = coorx1 - atominfo[atomid+1]; float s, y, t; s = atominfo[atomid] * (1.0f / sqrtf(dx1*dx1 + dysqpdzsq)); y = s - energycomp1; t = energyvalx1 + y; energycomp1 = (t - energyvalx1) - y; energyvalx1 = t; } ..

Say I have a C program that in pseudoish is: For i=0 to 10 x++ a=2+x*5 next Is the number of FLOPs for this (1 [x++] + 1 [x*5] + 1 [2+(x+5))] * 10[loop], for 30 FLOPS? I am having trouble understanding what a flop is. Note the [...] are indicating where I am getting my counts for "operations" from. For the purposes of FLOPS measurements, usually only additions and multiplications are included. Things like divisions, reciprocals, square roots, and transcendental functions are too expensive to include as a single operation, while things like loads and stores are too trivial. In other words, your

I have a friendly competition with couple of guys in the field of programming and recently we have become so interested in writing efficient code. Our challenge was to try to optimize the code (in sense of cpu time and complexity) at any cost (readability, reusability, etc). The problem is, now we need to compare our codes and see which approach is better comparing to the others but we don't know any tools for this purpose. My question is, are there some (any!) tools that takes a piece of code as input and calculates the number of flops or cpu instructions necessary for running it? Is there