Math library functions

Several common mathematical functions are included in a standard library. These functions (usually) include abs, dabs, iabs, mod, dmod, amod, exp, dexp, alog, dlog, sqrt, dsqrt, sin, cos, tan, cosh, sinh, tanh, and their double precision versions, as well as the inverse trig functions acos, asin, atan and their double precision versions, amax1, dmax1, amin1, dmin1, the random number ran (or rand or ranf), and the sign transfer sign, isign, dsign. Most of these are straightforward to use. The two not-so-obvious are

• ranf() or ranf(ISEED) which will produce a random number between 0 and 1. If the compiler requires it, the integer ISEED is a seed number which is used to generate the random output.}
• sign(x,y) will evaluate to |x|, if y .GE. 0, or to -|x|, if y .LT. 0. }