sed & awk, 2nd Edition

Arithmetic Functions

Nine of the built-in functions can be classified as arithmetic functions. Most of them take a numeric argument and return a numeric value. Table 9.1 summarizes these arithmetic functions.

Table 9.1. awk’s Built-In Arithmetic Functions

Awk Function	Description
cos(x)	Returns cosine of x (x is in radians).
exp(x)	Returns e to the power x.
int(x)	Returns truncated value of x.
log(x)	Returns natural logarithm (base-e) of x.
sin(x)	Returns sine of x (x is in radians).
sqrt(x)	Returns square root of x.
atan2(y,x)	Returns arctangent of y/x in the range -π to π.
rand( )	Returns pseudo-random number r, where 0 <= r < 1.
srand(x)	Establishes new seed for rand( ). If no seed is specified, uses time of day. Returns the old seed.

Trigonometric Functions

The trigonometric functions cos( ) and sin( ) work the same way, taking a single argument that is the size of an angle in radians and returning the cosine or sine for that angle. (To convert from degrees to radians, multiply the number by π/180.) The trigonometric function atan2( ) takes two arguments and returns the arctangent of their quotient. The expression

atan2(0, -1)

produces π.

The function exp( ) uses the natural exponential, which is also known as base-e exponentiation. The expression

exp(1)

returns the natural number 2.71828, the base of the natural logarithms, referred to as e. Thus, exp(x) is e to the x-th power.

The log( ) function gives the inverse of the exp( ) function, the natural logarithm of x. The sqrt( ) function takes ...