LA_INVERT
The LA_INVERT function uses LU decomposition to compute the inverse of a square array.
LA_INVERT is based on the following LAPACK routines:
|
Output Type |
LAPACK Routine |
|
Float |
sgetrf, sgetri |
|
Double |
dgetrf, dgetri |
|
Complex |
cgetrf, cgetri |
|
Double complex |
zgetrf, zgetri |
Examples
The following program computes the inverse of a square array:
; Create a square array.
array =[[1d, 2, 1], $
[4, 10, 15], $
[3, 7, 1]]
; Compute the inverse and check the error.
ainv = LA_INVERT(array)
PRINT, 'LA_INVERT Identity Matrix:'
PRINT, ainv ## array
When this program is compiled and run, IDL prints:
LA_INVERT Identity Matrix:
1.0000000 1.7763568e-015 6.6613381e-016 0.00000000 1.0000000 1.2212453e-015 0.00000000 0.00000000 1.0000000
Syntax
Result = LA_INVERT( A [, /DOUBLE] [, STATUS=variable] )
Return Value
The result is an array of the same dimensions as the input array.
Arguments
A
The n-by-n array to be inverted.
Keywords
DOUBLE
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.
STATUS
Set this keyword to a named variable that will contain the status of the computation. Possible values are:
- STATUS = 0: The computation was successful.
- STATUS > 0: The array is singular and the inverse could not be computed. The STATUS value specifies which value along the diagonal (starting at one) is zero.
Note: If STATUS is not specified, any error messages will be output to the screen.
Version History
|
5.6 |
Introduced |
Resources and References
For more details, see Anderson et al., LAPACK Users' Guide, 3rd ed., SIAM, 1999.