Calculates the cumulative distribution function (CDF) of a bivariate normal distribution. This function computes P(X <= a, Y <= b) where X and Y follow a bivariate normal distribution with correlation coefficient rho.
qBiNormal(a, b, rho)
The probability P(X <= a, Y <= b), a value between 0 and 1.
Numeric value, the upper limit for the first variable.
Numeric value, the upper limit for the second variable.
Numeric value between -1 and 1, the correlation coefficient.
The implementation uses numerical integration with Gauss-Legendre quadrature for accurate computation. Special cases for infinite bounds are handled separately.