cmath

The interface on my build system MacOS 10.6.3 for the POSIX math library is math.h, however on my target system the name of the interface file is cmath.h. At school we use cmath and I would like to be sure my project compiles when it is handed in, how is this achieved. The servers and workstations at school are x86 running Windows XP. The GCC is available on both platforms. In the C++ standard, the math library functions are defined in two headers: <cmath> contains them in the namespace std (e.g. std::sin ), while <math.h> contains them in the global namespace (so just sin ). There are further

I assume that abs and fabs are behaving different when using math.h . But when I use just cmath and std::abs , do I have to use std::fabs or fabs ? Or isn't this defined? In C++, it's always sufficient to use std::abs ; it's overloaded for all the numerical types. In C, abs only works on integers, and you need fabs for floating point values. These are available in C++ (along with all of the C library), but there's no need to use them. It's still okay to use fabs for double and float arguments. I prefer this because it ensures that if I accidentally strip the std:: off the abs , that the

I am developing a project which works with multiple arithmetic types. So I made a header, where the minimal requirements for a user defined arithmetic type are defined: user_defined_arithmetic.h : typedef double ArithmeticF; // The user chooses what type he // wants to use to represent a real number namespace arithmetic // and defines the functions related to that type { const ArithmeticF sin(const ArithmeticF& x); const ArithmeticF cos(const ArithmeticF& x); const ArithmeticF tan(const ArithmeticF& x); ... } What is troubling me is that when I use code like this: #include "user_defined

Given the following program: #include <cmath> int main() { std::abs(0u) ; } gcc and clang disagree on whether this is ill-formed. Using gcc with libstdc++ the code builds without error or warning ( see it live ), while using clang with libc++ it generates the following error ( see it live ): error: call to 'abs' is ambiguous std::abs(0u) ; ^~~~~~~~ Which result is correct? Should abs(0u) be ambiguous or not? MSalters points out an interesting related question: Template version of std::abs . Looks like libstdc++ is correct, this is not ill-formed, although we will see there are some doubts