Using the scalar library

The MASS scalar library libmass.a contains an accelerated set of frequently used math intrinsic functions that provide improved performance over the corresponding standard system library functions. The MASS scalar functions are used when explicitly linking libmass.a.

If you want to explicitly call the MASS scalar functions, you can take the following steps:

Provide the prototypes for the functions (except anint, cosisin, dnint, and sincos), by including math.h in your source files.
Provide the prototypes for anint, cosisin, dnint, and sincos, by including mass.h in your source files.
Link the MASS scalar library libmass.a with your application. For instructions, see Compiling and linking a program with MASS.

The MASS scalar functions accept double-precision parameters and return a double-precision result, or accept single-precision parameters and return a single-precision result, except sincos which gives 2 double-precision results. They are summarized in Table 1.

Table 1. MASS scalar functions
Double-precision function	Single-precision function	Description	Double-precision function prototype	Single-precision function prototype
acos	acosf	Returns the arccosine of `x`	double acos (double x);	float acosf (float x);
acosh	acoshf	Returns the hyperbolic arccosine of `x`	double acosh (double x);	float acoshf (float x);
	anint	Returns the rounded integer value of `x`		float anint (float x);
asin	asinf	Returns the arcsine of `x`	double asin (double x);	float asinf (float x);
asinh	asinhf	Returns the hyperbolic arcsine of `x`	double asinh (double x);	float asinhf (float x);
atan2	atan2f	Returns the arctangent of `x`/`y`	double atan2 (double x, double y);	float atan2f (float x, float y);
atan	atanf	Returns the arctangent of `x`	double atan (double x);	float atanf (float x);
atanh	atanhf	Returns the hyperbolic arctangent of `x`	double atanh (double x);	float atanhf (float x);
cbrt	cbrtf	Returns the cube root of `x`	double cbrt (double x);	float cbrtf (float x);
copysign	copysignf	Returns `x` with the sign of `y`	double copysign (double x,double y);	float copysignf (float x);
cos	cosf	Returns the cosine of `x`	double cos (double x);	float cosf (float x);
cosh	coshf	Returns the hyperbolic cosine of `x`	double cosh (double x);	float coshf (float x);
cosisin		Returns a complex number with the real part the cosine of `x` and the imaginary part the sine of `x`.	double_Complex cosisin (double);
dnint		Returns the nearest integer to `x` (as a double)	double dnint (double x);
erf	erff	Returns the error function of `x`	double erf (double x);	float erff (float x);
erfc	erfcf	Returns the complementary error function of `x`	double erfc (double x);	float erfcf (float x);
exp	expf	Returns the exponential function of `x`	double exp (double x);	float expf (float x);
expm1	expm1f	Returns (the exponential function of `x`) - 1	double expm1 (double x);	float expm1f (float x);
hypot	hypotf	Returns the square root of x² + y²	double hypot (double x, double y);	float hypotf (float x, float y);
lgamma	lgammaf	Returns the natural logarithm of the absolute value of the Gamma function of `x`	double lgamma (double x);	float lgammaf (float x);
log	logf	Returns the natural logarithm of `x`	double log (double x);	float logf (float x);
log10	log10f	Returns the base 10 logarithm of `x`	double log10 (double x);	float log10f (float x);
log1p	log1pf	Returns the natural logarithm of (`x` + 1)	double log1p (double x);	float log1pf (float x);
pow	powf	Returns `x` raised to the power `y`	double pow (double x, double y);	float powf (float x, float y);
rsqrt		Returns the reciprocal of the square root of `x`	double rsqrt (double x);
sin	sinf	Returns the sine of `x`	double sin (double x);	float sinf (float x);
sincos		Sets `s` to the sine of `x` and `c` to the cosine of `x`	void sincos (double x, double* s, double* c);
sinh	sinhf	Returns the hyperbolic sine of `x`	double sinh (double x);	float sinhf (float x);
sqrt		Returns the square root of `x`	double sqrt (double x);
tan	tanf	Returns the tangent of `x`	double tan (double x);	float tanf (float x);
tanh	tanhf	Returns the hyperbolic tangent of `x`	double tanh (double x);	float tanhf (float x);

Notes:

The trigonometric functions (sin, cos, tan) return NaN (Not-a-Number) for large arguments (where the absolute value is greater than 2⁵⁰pi).
In some cases, the MASS functions are not as accurate as the ones in the libm.a library, and they might handle edge cases differently (sqrt(Inf), for example).
See the Mathematical Acceleration Subsystem website for accuracy comparisons with libm.a.