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### LA_INVERT

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.

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