FRANNOR - functions to generate a pseudo-random float normally distributed
		with N(0,1); i.e., with zero mean and unit variance.

frannor		return a normally distributed random float
srannor		seed random number generator for normal distribution

Function Prototypes:
float frannor (void);
void srannor (int seed);

frannor:
Input:		(none)
Returned:	normally distributed random float

srannor:
Input:
seed		different seeds yield different sequences of random numbers.

Notes:
Adapted from subroutine rnor in Kahaner,  Moler and Nash (1988)
which in turn was based on  an algorithm by 
Marsaglia and Tsang (1984).

References:
Numerical Methods and Software", D.
Kahaner, C. Moler, S. Nash, Prentice Hall, 1988.

Marsaglia G. and Tsang, W. W., 1984,
A fast, easily implemented method for sampling from decreasing or symmetric
unimodal density functions:  SIAM J. Sci. Stat. Comput., v. 5, no. 2,
p. 349-359.

Author:  Dave Hale, Colorado School of Mines, 01/21/89