{
	Compute overlap between two normal distribution functions,
	defined by mean1, mean2, stdev1 and stdev2.

	2/10/95		Greg Ward

	relies on gauss.cal and norm.cal
}
min(a,b) : if(a-b, b, a);
max(a,b) : if(a-b, a, b);

Z1(u) = Z((u - mean1)/stdev1) / stdev1;
Z2(u) = Z((u - mean2)/stdev2) / stdev2;

f(u) = min(Z1(u),Z2(u));

xmin = min(mean1-3*stdev1, mean2-3*stdev2);
xmax = max(mean1+3*stdev1, mean2+3*stdev2);