#### 8.4.12 Matrix properties

The following functions are defined for real and complex matrices. For complex matrices both the real and imaginary parts must satisfy the conditions.

Function: int gsl_matrix_isnull (const gsl_matrix * m)
Function: int gsl_matrix_ispos (const gsl_matrix * m)
Function: int gsl_matrix_isneg (const gsl_matrix * m)
Function: int gsl_matrix_isnonneg (const gsl_matrix * m)

  These functions return 1 if all the elements of the matrix m are zero, strictly positive, strictly negative, or non-negative respectively, and 0 otherwise. To test whether a matrix is positive-definite, use the Cholesky decomposition (see Cholesky Decomposition).

Function: int gsl_matrix_equal (const gsl_matrix * a, const gsl_matrix * b)

  This function returns 1 if the matrices a and b are equal (by comparison of element values) and 0 otherwise.