UNIFM2 - Uniform random number generator any range.

val = unifm2(seed, mean, width)

val: will be in the range "mean-width/2<val<mean+width/2"
seed: is a real value used as a seed. This will be ignored on all but the first call.
mean: is a real value specifying the middle of the range.
width: is a real value specifying the width of the range.

UNIFM2 is used to generate a uniform random variable over some arbitrary range.