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7.4.8 <mathf.h>

Performs various mathematical operations.

<mathf.h> declares mathematical functions and defines macros in single-precision format. The mathematical functions and macros used here do not follow the ANSI specifications. Each function receives float-type arguments and returns a float-type value.

The following constants (macros) are all implementation-defined.

Type	Definition Name	Description
Constant (macro)	EDOM	Indicates the value to be set in errno if the value of a parameter input to a function is outside the range of values defined in the function.
	ERANGE	Indicates the value to be set in errno if the result of a function cannot be represented as a float type value, or if an overflow or an underflow occurs.
	HUGE_VALF HUGE_VAL HUGE_VALL	Indicates the value for the function return value if the result of a function overflows.
Function	acosf	Calculates the arc cosine of a floating-point number.
	asinf	Calculates the arc sine of a floating-point number.
	atanf	Calculates the arc tangent of a floating-point number.
	atan2f	Calculates the arc tangent of the result of a division of two floating-point numbers.
	cosf	Calculates the cosine of a floating-point radian value.
	sinf	Calculates the sine of a floating-point radian value.
	tanf	Calculates the tangent of a floating-point radian value.
	coshf	Calculates the hyperbolic cosine of a floating-point number.
	sinhf	Calculates the hyperbolic sine of a floating-point number.
	tanhf	Calculates the hyperbolic tangent of a floating-point number.
	expf	Calculates the exponential function of a floating-point number.
	frexpf	Breaks a floating-point number into a [0.5, 1.0) value and a power of 2.
	ldexpf	Multiplies a floating-point number by a power of 2.
	logf	Calculates the natural logarithm of a floating-point number.
	log10f	Calculates the base-ten logarithm of a floating-point number.
	modff	Breaks a floating-point number into integral and fractional parts.
	powf	Calculates a power of a floating-point number.
	sqrtf	Calculates the positive square root of a floating-point number.
	ceilf	Calculates the smallest integral value not less than or equal to the given floating-point number.
	fabsf	Calculates the absolute value of a floating-point number.
	floorf	Calculates the largest integral value not greater than or equal to the given floating-point number.
	fmodf	Calculates the remainder of a division of two floating-point numbers.

Operation in the event of an error is described below.

(1)	Domain error

A domain error occurs if the value of a parameter input to a function is outside the domain over which the mathematical function is defined. In this case, the value of EDOM is set in errno. The function return value in implementation-defined.

(2)	Range error

A range error occurs if the result of a function cannot be represented as a float type value. In this case, the value of ERANGE is set in errno. If the result overflows, the function returns the value of HUGE_VALF, with the same sign as the correct value of the function. If the result underflows, 0 is returned as the return value.

Notes 1.

If there is a possibility of a domain error resulting from a <mathf.h> function call, it is dangerous to use the resultant value directly. The value of errno should always be checked before using the result in such cases.

[Format]

         1  x=asinf(a);

         2  if (errno==EDOM)

         3      printf ("error\n");

         4  else

         5      printf ("result is : %f\n",x);

In line 1, the arc sine value is computed using the asinf function. If the value of argument a is outside the asinf function domain [–1.0, 1.0], the EDOM value is set in errno. Line 2 determines whether a domain error has occurred. If a domain error has occurred, error is output in line 3. If there is no domain error, the arc sine value is output in line 5.

Notes 2.

Whether or not a range error occurs depends on the internal representation format of floating-point types determined by the compiler. For example, if an internal representation format that allows an infinity to be represented as a value is used, <mathf.h> library functions can be implemented without causing range errors.

Implementation-Defined Specifications

Item	Compiler Specifications
Value returned by a mathematical function if an input argument is out of the range	A not-a-number is returned. For details on the format of not-a-numbers, refer to section 4.1.6 (5) Floating-Point Number Specifications.
Whether errno is set to the value of macro ERANGE if an underflow error occurs in a mathematical function	Not specified
Whether a range error occurs if the second argument in the fmodf function is 0	A range error occurs.