Linear index upper triangular matrix
The equations going from linear index to (i,j) index are i = n – 2 – floor(sqrt(-8*k + 4*n*(n-1)-7)/2.0 – 0.5) j = k + i + 1 – n*(n-1)/2 + (n-i)*((n-i)-1)/2 The inverse operation, from (i,j) index to linear index is k = (n*(n-1)/2) – (n-i)*((n-i)-1)/2 + j – i – 1 Verify in … Read more