Variance of Legendre polynomials
y=legendre_variance(n)
a 1-by-1 matrix of doubles, integer value, n>=0.
a matrix of doubles, the variance
Compute the variance
for n=0,1,2,..., where X is a uniform random variable in the interval [-1,1].
legendre_variance(0) legendre_variance(1) legendre_variance(2)