Inverse condition number.

Syntax

c = rcond(A)

Argument

Name

Description

A

A square matrix; real or complex.

Outputs

Name

Description

C

A real scalar (matrix size 1 x 1).

Example

Syntax

A =   [0.8147    0.6324    0.9575    0.9572;

       0.9058    0.0975    0.9649    0.4854;

       0.1270    0.2785    0.1576    0.8003;

       0.9134    0.5469    0.9706    0.1419];

C = rcond(A);

print('C = ', C)

Result

C = rcond(A);

print('C = ', C)

Comments

c = rcond(A) returns the 1-norm estimate of the reciprocal condition number.

If A is well conditioned, rcond(A) is near 1.0.

If A is badly conditioned, rcond(A) is near 0.0.

The rcond function is far more efficient than the explicit calculation: C = 1/(Norm(A, 1) * Norm(Inv(A), 1))

The rcond function uses LAPACK functions (DLANGE, DGETRF, DGECON for real numbers and ZLANGE, ZGETRF, ZGECON for complex numbers).

See Also:

eig