inline bool backslash(const mat& A, const vec & b, vec & x){ x = A.jacobiSvd(ComputeThinU | ComputeThinV).solve(b); return true; }
inline bool backslash(const mat& A, const vec & b, vec & x){ x = A.jacobiSvd(ComputeThinU | ComputeThinV).solve(b); return true; }