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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 13.5).