The LA_DETERM function uses LU decomposition to compute the determinant of a square array.

This routine is written in the IDL language. Its source code can be found in the file in the lib subdirectory of the IDL distribution.


The following program computes the determinant of a square array:

; Create a square array
array =[[1d, 2, 1], $
   [4, 10, 15], $
   [3, 7, 1]]
; Compute the determinant.
adeterm = LA_DETERM(array)
PRINT, 'LA_DETERM:', adeterm

When this program is compiled and run, IDL prints:



Result = LA_DETERM( A [, /CHECK] [, /DOUBLE] [, ZERO=value] )

Return Value

The result is a scalar of the same type as the input array.



An n-by-n real or complex array.



Set this keyword to check A for any singularities. The determinant of a singular array is returned as zero if this keyword is set. Run-time errors may result if A is singular and this keyword is not set.


Set this keyword to use double-precision for computations and to return a double-precision (real or complex) result. Set DOUBLE = 0 to use single-precision for computations and to return a single-precision (real or complex) result. The default is /DOUBLE if A is double precision, otherwise the default is DOUBLE = 0.


Use this keyword to set the absolute value of the floating-point zero. A floating-point zero on the main diagonal of a triangular array results in a zero determinant. For single-precision inputs, the default value is 1.0 x 10-6. For double-precision inputs, the default value is 1.0 x 10-12. Setting this keyword to a value less than the default may improve the precision of the result.

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