In the old days, linkers were slow and separating the mostly unused math code from the rest made the compilation process go faster. The difference is not so great today, so you can add the -lm option to your default conpiler configuration.

Note that the header <math.h> (or any other header) does not contain code. It contains information about the code, specifically how to call functions. The code itself is in a library. I mean, your program does not use the "<math.h> library", it uses the math library and uses the prototypes declared in the <math.h> header.

In the old days, linkers were slow and separating the mostly unused math code from the rest made the compilation process go faster. The difference is not so great today, so you can add the -lm option to your default compiler configuration.

Note that the header <math.h> (or any other header) does not contain code. It contains information about the code, specifically how to call functions. The code itself is in a library. I mean, your program does not use the "<math.h> library", it uses the math library and uses the prototypes declared in the <math.h> header.