Correlation coefficient r between two series x(i) and y(i) with missing data, where i=1,...,n.

input: x(n),y(n),undef

undef is missing data however, if ax or sx is still undefined,

it will be -9.99e33 whatever the input undef is.

output: r and nr

nr is the effective number of independent and defined values

simultianeuosly in two series. 　　

By Dr. LI Jianping, Decmber 5, 2001.-By Dr. LI Jianping, Decmber 5, 2001