Why do you have to link the math library in C?

Question

If I include or in a C program I don\'t have to link these when compiling but I do have to link to

Answer 1

Remember that C is an old language and that FPUs are a relatively recent phenomenon. I first saw C on 8-bit processors where it was a lot of work to do even 32-bit integer arithmetic. Many of these implementations didn't even have a floating point math library available!

Even on the first 68000 machines (Mac, Atari ST, Amiga), floating point coprocessors were often expensive add-ons.

To do all that floating point math, you needed a pretty sizable library. And the math was going to be slow. So you rarely used floats. You tried to do everything with integers or scaled integers. When you had to include math.h, you gritted your teeth. Often, you'd write your own approximations and lookup tables to avoid it.

Trade-offs existed for a long time. Sometimes there were competing math packages called "fastmath" or such. What's the best solution for math? Really accurate but slow stuff? Inaccurate but fast? Big tables for trig functions? It wasn't until coprocessors were guaranteed to be in the computer that most implementations became obvious. I imagine that there's some programmer out there somewhere right now, working on an embedded chip, trying to decide whether to bring in the math library to handle some math problem.

That's why math wasn't standard. Many or maybe most programs didn't use a single float. If FPUs had always been around and floats and doubles were always cheap to operate on, no doubt there would have been a "stdmath".