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Test Your Knowledge in Computers #308
Difficulty: Easy
The first computer bug was created by a broken keyboard input.
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# ztptri(3) [centos man page]

```ztptri.f(3)							      LAPACK							       ztptri.f(3)

NAME
ztptri.f -

SYNOPSIS
Functions/Subroutines
subroutine ztptri (UPLO, DIAG, N, AP, INFO)
ZTPTRI

Function/Subroutine Documentation
subroutine ztptri (characterUPLO, characterDIAG, integerN, complex*16, dimension( * )AP, integerINFO)
ZTPTRI

Purpose:

ZTPTRI computes the inverse of a complex upper or lower triangular
matrix A stored in packed format.

Parameters:
UPLO

UPLO is CHARACTER*1
= 'U':  A is upper triangular;
= 'L':  A is lower triangular.

DIAG

DIAG is CHARACTER*1
= 'N':  A is non-unit triangular;
= 'U':  A is unit triangular.

N

N is INTEGER
The order of the matrix A.  N >= 0.

AP

AP is COMPLEX*16 array, dimension (N*(N+1)/2)
On entry, the upper or lower triangular matrix A, stored
columnwise in a linear array.  The j-th column of A is stored
in the array AP as follows:
if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
if UPLO = 'L', AP(i + (j-1)*((2*n-j)/2) = A(i,j) for j<=i<=n.
See below for further details.
On exit, the (triangular) inverse of the original matrix, in
the same packed storage format.

INFO

INFO is INTEGER
= 0:  successful exit
< 0:  if INFO = -i, the i-th argument had an illegal value
> 0:  if INFO = i, A(i,i) is exactly zero.  The triangular
matrix is singular and its inverse can not be computed.

Author:
Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Date:
November 2011

Further Details:

A triangular matrix A can be transferred to packed storage using one
of the following program segments:

UPLO = 'U':		      UPLO = 'L':

JC = 1			    JC = 1
DO 2 J = 1, N		    DO 2 J = 1, N
DO 1 I = 1, J		       DO 1 I = J, N
AP(JC+I-1) = A(I,J)		  AP(JC+I-J) = A(I,J)
1    CONTINUE			  1    CONTINUE
JC = JC + J		       JC = JC + N - J + 1
2 CONTINUE			  2 CONTINUE

Definition at line 118 of file ztptri.f.

Author
Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2							  Tue Sep 25 2012						       ztptri.f(3)```

## Check Out this Related Man Page

```stptri.f(3)							      LAPACK							       stptri.f(3)

NAME
stptri.f -

SYNOPSIS
Functions/Subroutines
subroutine stptri (UPLO, DIAG, N, AP, INFO)
STPTRI

Function/Subroutine Documentation
subroutine stptri (characterUPLO, characterDIAG, integerN, real, dimension( * )AP, integerINFO)
STPTRI

Purpose:

STPTRI computes the inverse of a real upper or lower triangular
matrix A stored in packed format.

Parameters:
UPLO

UPLO is CHARACTER*1
= 'U':  A is upper triangular;
= 'L':  A is lower triangular.

DIAG

DIAG is CHARACTER*1
= 'N':  A is non-unit triangular;
= 'U':  A is unit triangular.

N

N is INTEGER
The order of the matrix A.  N >= 0.

AP

AP is REAL array, dimension (N*(N+1)/2)
On entry, the upper or lower triangular matrix A, stored
columnwise in a linear array.  The j-th column of A is stored
in the array AP as follows:
if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
if UPLO = 'L', AP(i + (j-1)*((2*n-j)/2) = A(i,j) for j<=i<=n.
See below for further details.
On exit, the (triangular) inverse of the original matrix, in
the same packed storage format.

INFO

INFO is INTEGER
= 0:  successful exit
< 0:  if INFO = -i, the i-th argument had an illegal value
> 0:  if INFO = i, A(i,i) is exactly zero.  The triangular
matrix is singular and its inverse can not be computed.

Author:
Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Date:
November 2011

Further Details:

A triangular matrix A can be transferred to packed storage using one
of the following program segments:

UPLO = 'U':		      UPLO = 'L':

JC = 1			    JC = 1
DO 2 J = 1, N		    DO 2 J = 1, N
DO 1 I = 1, J		       DO 1 I = J, N
AP(JC+I-1) = A(I,J)		  AP(JC+I-J) = A(I,J)
1    CONTINUE			  1    CONTINUE
JC = JC + J		       JC = JC + N - J + 1
2 CONTINUE			  2 CONTINUE

Definition at line 118 of file stptri.f.

Author
Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2							  Tue Sep 25 2012						       stptri.f(3)```