GAWK: Effective AWK Programming

Chapter 8: Functions 131int(x)sqrt(x)exp(x)log(x)sin(x)cos(x)This returns the nearest integer to x, located between x and zero and truncatedtoward zero.For example, int(3) is 3, int(3.9) is 3, int(-3.9) is −3, and int(-3) is −3as well.This returns the positive square root of x. gawk reports an error if x is negative.Thus, sqrt(4) is 2.This returns the exponential of x (e ^ x) or reports an error if x is out ofrange. The range of values x can have depends on your machine’s floatingpointrepresentation.This returns the natural logarithm of x, if x is positive; otherwise, it reports anerror.This returns the sine of x, with x in radians.This returns the cosine of x, with x in radians.atan2(y, x)This returns the arctangent of y / x in radians.rand()This returns a random number. The values of rand are uniformly distributedbetween zero and one. The value could be zero but is never one. 1Often random integers are needed instead. Following is a user-defined functionthat can be used to obtain a random non-negative integer less than n:function randint(n) {return int(n * rand())}The multiplication produces a random number greater than zero and less thann. Using int, this result is made into an integer between zero and n − 1,inclusive.The following example uses a similar function to produce random integers betweenone and n. This program prints a new random number for each inputrecord:# Function to roll a simulated die.function roll(n) { return 1 + int(rand() * n) }# Roll 3 six-sided dice and# print total number of points.{printf("%d points\n",roll(6)+roll(6)+roll(6))}Caution: In most awk implementations, including gawk, rand starts generatingnumbers from the same starting number, or seed, each time you run awk. Thus,1 The C version of rand is known to produce fairly poor sequences of random numbers. However, nothingrequires that an awk implementation use the C rand to implement the awk version of rand. In fact, gawkuses the BSD random function, which is considerably better than rand, to produce random numbers.