Classic Shell Scripting

Numeric Functions

awk provides the elementary numeric functions listed in Table 9-5Table 9-5. Most of them are common to many programming languages, and their accuracy depends on the quality of the underlying native mathematical-function library.

Table 9-6. Elementary numeric functions

Function	Description
atan2( y, x )	Return the arctangent of y/x as a value in - to +.
cos( x )	Return the cosine of x (measured in radians) as a value in -1 to +1.
exp( x )	Return the exponential of x, e x.
int( x )	Return the integer part of x, truncating toward zero.
log( x )	Return the natural logarithm of x.
rand( )	Return a uniformly distributed pseudorandom number, r, such that 0 r < 1.
sin( x )	Return the sine of x (measured in radians) as a value in -1 to +1.
sqrt( x )	Return the square root of x.
srand( x )	Set the pseudorandom-number generator seed to x, and return the current seed. If x is omitted, use the current time in seconds, relative to the system epoch. If srand( ) is not called, awk starts with the same default seed on each run; mawk does not.

The pseudorandom-number generator functions rand() and srand( ) are the area of largest variation in library functions in different awk implementations because some of them use native system-library functions instead of their own code, and the pseudorandom-number generating algorithms and precision vary. Most algorithms for generation of such numbers step through a sequence from a finite set without repetition, and the sequence ultimately ...