Document revision date: 19 July 1999

Interface

F_TYPE drem (F_TYPE x, F_TYPE y)

Description

drem() returns the remainder r = x-n*y, where n = rint(x/y). Additionally, if |n-x/y|=1/2, then n is even. The remainder is computed exactly, and |r| is less than or equal to |y|/2. The drem() and remainder() functions are aliases of each other.

IEEE Std 754 defines drem(x,0) and drem(infinity,y) to be invalid operations that produce a NaN.

Exceptions

Interface

F_TYPE erf (F_TYPE x)

F_TYPE erfc (F_TYPE x)

Description

erf() returns the value of the error function where erf(x) equals (2 * sqrt(pi)) times the area under the curve e**(-t**2) between 0 and x.

erfc() returns (1.0-erf(x)). The erfc() function can result in an underflow as x gets large.

Exceptions

Interface

F_TYPE exp (F_TYPE x)

F_TYPE expm1 (F_TYPE x)

Description

exp() computes the value of the exponential function, defined as e**x, where e is the constant used as a base for natural logarithms.

expm1() computes exp(x)-1 accurately, even for tiny x.

Exceptions

See Also

Interface

F_TYPE fabs (F_TYPE x)

Description

fabs() computes the absolute value of x.

Exceptions

Interface

int finite (F_TYPE x)

Description

finite() returns the integer value 1 (true) or 0 (false).

finite(x) = 1 when -infinity < x < +infinity.

finite(x) = 0 when |x| = infinity or x is a NaN.

Exceptions

Interface

F_TYPE floor (F_TYPE x)

Description

floor() returns the largest floating-point integer value less than or equal to x.

Exceptions

Interface

F_TYPE fmod (F_TYPE x, F_TYPE y)

Description

fmod() computes the floating-point remainder of x modulo y. It returns the remainder r = x-n*y, where n = trunc(x/y). The remainder is computed exactly.

The result has the same sign as x and a magnitude less than the magnitude of y.

Exceptions

Interface

int fp_class (F_TYPE x)

Description

These routines determine the class of IEEE floating-point values. They return one of the constants in the file <fp_class.h> and never cause an exception, even for signaling NaNs. These routines implement the recommended function class(x) in the appendix of the IEEE Std 754. The constants in <fp_class.h> refer to the following classes of values:

Constant	Class
FP_SNAN	Signaling NaN (Not-a-Number)
FP_QNAN	Quiet NaN (Not-a-Number)
FP_POS_INF	+Infinity
FP_NEG_INF	-Infinity
FP_POS_NORM	Positive normalized
FP_NEG_NORM	Negative normalized
FP_POS_DENORM	Positive denormalized
FP_NEG_DENORM	Negative denormalized
FP_POS_ZERO	+0.0 (positive zero)
FP_NEG_ZERO	-0.0 (negative zero)

Exceptions

See Also

Interface

F_TYPE frexp (F_TYPE x, int *n)

Description

frexp() breaks a floating-point number into a normalized fraction and an integral power of 2. It stores the integer in the int object pointed to by the n parameter and returns the fraction part.

Exceptions

Interface

F_TYPE hypot (F_TYPE x, F_TYPE y)

Description

hypot() computes the length of the hypotenuse of a right triangle, where x and y represent the perpendicular sides of the triangle.

hypot(x,y) is defined as the square root of (x**2 + y**2) and returns the same value as cabs(x,y).

Exceptions

See Also

Interface

int ilogb (F_TYPE x)

Description

ilogb() returns the integral part of log_r(|x|) as a signed integral value, for x is not equal to 0, where r is the radix of the machine's floating point arithmetic.

Exceptions

Interface

int isnan (F_TYPE x)

Description

isnan() returns 1 (true) if x is NaN (the IEEE floating-point reserved Not-a-Number value) and 0 (false) otherwise.

Exceptions

Interface

F_TYPE ldexp (F_TYPE x, int n)

Description

ldexp() multiplies a floating-point number, x, by 2**n.

Exceptions

See Also

Interface

F_TYPE lgamma (F_TYPE x)

Description

lgamma() returns the logarithm of the absolute value of gamma of x, or ln(|G(x)|), where G is the gamma function. The sign of gamma of x is returned in the external integer variable signgam as +1 or -1. The x parameter cannot be 0 or a negative integer.

gamma() returns the natural log of the gamma function and so is functionally equivalent to lgamma(). Because of this, gamma() is marked TO BE WITHDRAWN in the X/Open Portability Guide, Revision 4 (XPG4).

Exceptions

See Also

Interface

F_TYPE ln (F_TYPE x)

F_TYPE log2 (F_TYPE x)

F_TYPE log10 (F_TYPE x)

F_TYPE log1p (F_TYPE y)

Description

ln() computes the natural (base e) logarithm of x.

log2() computes the base 2 logarithm of x.

log10() computes the common (base 10) logarithm of x.

log1p() computes ln(1+y) accurately, even for tiny y.

Exceptions

Interface

F_TYPE logb (F_TYPE x)

Description

logb() returns a signed integer converted to double-precision floating-point and so chosen that 1 <= |x|/2**n < 2 unless x = 0 or |x| = infinity.

IEEE Std 754 defines logb(+infinity) = +infinity and logb(0) = -infinity. The latter is required to signal division by zero.

Exceptions

Interface

F_TYPE modf (F_TYPE x, F_TYPE *n)

Description

modf() splits a floating-point number x into a fractional part f and an integer part i such that |f| < 1.0 and (f + i) = x. Both f and i have the same sign as x. modf() returns f and stores i into the location pointed to by n.

Exceptions

Interface

F_TYPE nextafter (F_TYPE x, F_TYPE y)

Description

nextafter() returns the machine-representable number next to x in the direction y.

Exceptions

See Also

Interface

F_TYPE nint (F_TYPE x)

Description

nint() returns the nearest integral value to x, except halfway cases are rounded to the integral value larger in magnitude. This function corresponds to the Fortran generic intrinsic function nint().

Exceptions

Interface

F_TYPE pow (F_TYPE x, F_TYPE y)

Description

pow() raises a floating-point base x to a floating-point exponent y. The value of pow(x,y) is computed as e**(y ln(x)) for positive x. If x is 0 or negative, see your language reference manual.

Passing a NaN input value to pow() produces a NaN result for nonzero values of y. For pow(NaN,0), see your language reference manual.

Exceptions

See Also

Interface

F_TYPE random (int *n)

Description

random() is a general random number generator. The argument to the random function is an integer passed by reference. There are no restrictions on the input argument, although it should be initialized to different values on separate runs in order to obtain different random sequences. This function must be called again to obtain the next pseudorandom number. The argument is updated automatically.

The result is a floating-point number that is uniformly distributed in the interval (0.0,1.0).

Exceptions

Interface

F_TYPE remainder (F_TYPE x, F_TYPE y)

Description

remainder() returns the remainder r = x-n*y, where n = rint(x/y). Additionally, if |n-x/y|=1/2, then n is even. Consequently, the remainder is computed exactly, and |r| is less than or equal to |y|/2. The drem() and remainder() functions are aliases of each other.

IEEE Std 754 defines remainder(x,0) and remainder(infinity,y) to be invalid operations that produce a NaN.

Exceptions

Interface

F_TYPE rint (F_TYPE x)

Description

rint() rounds x to an integral value according to the current IEEE rounding direction specified by the user.

Exceptions

Interface

F_TYPE scalb (F_TYPE x, F_TYPE y)

Description

scalb() = x*(2**y) computed, for integer y.

Exceptions

See Also

Interface

F_TYPE sin (F_TYPE x)

F_TYPE sind (F_TYPE x)

Description

sin() computes the sine of x, measured in radians.

sind() computes the sine of x, measured in degrees.

Exceptions

See Also

Interface

F_COMPLEX sincos (F_TYPE x)

F_COMPLEX sincosd (F_TYPE x)

Description

sincos() computes both the sine and cosine of x, measured in radians.

sincosd() computes both the sine and cosine of x, measured in degrees.

sincos(x) is defined as (sin x + icos y).

Exceptions

Interface

F_TYPE sinh (F_TYPE x)

Description

sinh() computes the hyperbolic sine of x.

sinh(x) is defined as (exp(x)-exp(-x))/2.

Exceptions

See Also

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