What's the relative speed of floating point add vs. floating point multiply

Question

A decade or two ago, it was worthwhile to write numerical code to avoid using multiplies and divides and use addition and subtraction instead. A good example is using forwa

Answer 1

The speed difference of * / vs + - depends on your processor architecture. In general and with x86 in particular the speed difference has become less with modern processors. * should be close to +, when in doubt: just experiment. If you have a really hard problem with lots of FP operations also consider using your GPU (GeForce, ...) which works as a vector processor.