Overview
As explained in Chapter 8, both C and C++ originally supported the same set of 22 math functions. However, as C++ matured, it added overloaded versions of these original functions. Then, C99 greatly increased the size of the C math library in ways that C++ does not support. The net result of these changes is that today, the C and C++ math libraries have diverged, although both still support the original core set of math functions. Because of the differences between C and C++ in this area, the C math functions (including those added by C99) are described in Chapter 8. This chapter describes the math functions defined by C++.
In C++, the math functions require the header <cmath>. In addition to declaring the math functions, this header defines the macro called HUGE_VAL. The macros EDOM and ERANGE are also used by the math functions. These macros are defined in the header <cerrno>. If an argument to a math function is not in the domain for which it is defined, an implementation-defined value is returned, and the built-in global integer variable errno is set equal to EDOM. If a routine produces a result that is too large to be represented, an overflow occurs. This causes the routine to return HUGE_VAL, and errno is set to ERANGE, indicating a range error. If an underflow happens, the function returns zero and sets errno to ERANGE.
C++ supports the original math functions defined by C89. However, in C89, these functions operate only on floating-point values of type double. To these functions, C++ adds overloaded versions that explicitly accommodate values of type float and long double. The operation of the functions is otherwise unchanged.
acos
#include <cmath>float acos(float arg);double acos(double arg); long double acos(long double arg);
The acos( ) function returns the arc cosine of arg. The argument to acos( ) must be in the range –1 to 1; otherwise, a domain error will occur.
Related functions are asin( ), atan( ), atan2( ), sin( ), cos( ), tan( ), sinh( ), cosh( ), and tanh( ).
asin
#include <cmath>float asin(float arg);double asin(double arg); long double asin(long double arg);
The asin( ) function returns the arc sine of arg. The argument to asin( ) must be in the range –1 to 1; otherwise, a domain error will occur.
Related functions are acos( ), atan( ), atan2( ), sin( ), cos( ), tan( ), sinh( ), cosh( ), and tanh( ).
atan
#include <cmath>float atan(float arg);double atan(double arg); long double atan(long double arg);
The atan( ) function returns the arc tangent of arg.
Related functions are asin( ), acos( ), atan2( ), tan( ), cos( ), sin( ), sinh( ), cosh( ), and tanh( ).
atan2
#include <cmath>float atan2(float y, float x);double atan2(double y, double x); long double atan2(long double y, long double x);
The atan2( ) function returns the arc tangent of y/x. It uses the signs of its arguments to compute the quadrant of the return value.
Related functions are asin( ), acos( ), atan( ), tan( ), cos( ), sin( ), sinh( ), cosh( ), and tanh( ).
atan
#include <cmath>float atan(float arg);double atan(double arg); long double atan(long double arg);
The atan( ) function returns the arc tangent of arg.
Related functions are asin( ), acos( ), atan2( ), tan( ), cos( ), sin( ), sinh( ), cosh( ), and tanh( ).
atan2
#include <cmath>float atan2(float y, float x);double atan2(double y, double x); long double atan2(long double y, long double x);
The atan2( ) function returns the arc tangent of y/x. It uses the signs of its arguments to compute the quadrant of the return value.
Related functions are asin( ), acos( ), atan( ), tan( ), cos( ), sin( ), sinh( ), cosh( ), and tanh( ).
ceil
#include <cmath>float ceil(float num);double ceil(double num); long double ceil(long double num);
The ceil( ) function returns the smallest integer (represented as a floating-point value) not less than num. For example, given 1.02, ceil( ) would return 2.0. Given –1.02, ceil( ) would return –1.
cos
#include <cmath>float cos(float arg);double cos(double arg); long double cos(long double arg);
The cos( ) function returns the cosine of arg. The value of arg must be in radians.
