Makes NaN an illegal value for ANORM on input of GECON. Let NaNs prop…

…agate in the computation of RCOND
Reference-LAPACK · Nov 8, 2023 · 90b06e0 · 90b06e0
1 parent 09abbd0
commit 90b06e0
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Showing 4 changed files with 32 additions and 16 deletions.
diff --git a/SRC/cgecon.f b/SRC/cgecon.f
@@ -105,7 +105,12 @@
 *> \verbatim
 *>          INFO is INTEGER
 *>          = 0:  successful exit
-*>          < 0:  if INFO = -i, the i-th argument had an illegal value
+*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
+*>                NaNs are illegal values for ANORM, and they propagate to
+*>                the output parameter RCOND.
+*>                Infinity values are valid inputs for ANORM, because the values
+*>                in A can still be finite and, thus, norm of the inverse can be
+*>                computed as a strictly positive number.
 *>          = 1:  RCOND = NaN.
 *> \endverbatim
 *
@@ -201,7 +206,7 @@ SUBROUTINE CGECON( NORM, N, A, LDA, ANORM, RCOND, WORK, RWORK,
          RETURN
       ELSE IF( SISNAN( ANORM ) ) THEN
          RCOND = ANORM
-         INFO = 1
+         INFO = -5
          RETURN
       END IF
 *
@@ -260,8 +265,7 @@ SUBROUTINE CGECON( NORM, N, A, LDA, ANORM, RCOND, WORK, RWORK,
 *
 *     Compute the estimate of the reciprocal condition number.
 *
-      IF( AINVNM.NE.ZERO )
-     $   RCOND = ( ONE / AINVNM ) / ANORM
+      RCOND = ( ONE / AINVNM ) / ANORM
 *
 *     Check for NaNs
 *

diff --git a/SRC/dgecon.f b/SRC/dgecon.f
@@ -105,7 +105,12 @@
 *> \verbatim
 *>          INFO is INTEGER
 *>          = 0:  successful exit
-*>          < 0:  if INFO = -i, the i-th argument had an illegal value
+*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
+*>                NaNs are illegal values for ANORM, and they propagate to
+*>                the output parameter RCOND.
+*>                Infinity values are valid inputs for ANORM, because the values
+*>                in A can still be finite and, thus, norm of the inverse can be
+*>                computed as a strictly positive number.
 *>          = 1:  RCOND = NaN.
 *> \endverbatim
 *
@@ -194,7 +199,7 @@ SUBROUTINE DGECON( NORM, N, A, LDA, ANORM, RCOND, WORK, IWORK,
          RETURN
       ELSE IF( DISNAN( ANORM ) ) THEN
          RCOND = ANORM
-         INFO = 1
+         INFO = -5
          RETURN
       END IF
 *
@@ -252,8 +257,7 @@ SUBROUTINE DGECON( NORM, N, A, LDA, ANORM, RCOND, WORK, IWORK,
 *
 *     Compute the estimate of the reciprocal condition number.
 *
-      IF( AINVNM.NE.ZERO )
-     $   RCOND = ( ONE / AINVNM ) / ANORM
+      RCOND = ( ONE / AINVNM ) / ANORM
 *
 *     Check for NaNs
 *

diff --git a/SRC/sgecon.f b/SRC/sgecon.f
@@ -105,7 +105,12 @@
 *> \verbatim
 *>          INFO is INTEGER
 *>          = 0:  successful exit
-*>          < 0:  if INFO = -i, the i-th argument had an illegal value
+*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
+*>                NaNs are illegal values for ANORM, and they propagate to
+*>                the output parameter RCOND.
+*>                Infinity values are valid inputs for ANORM, because the values
+*>                in A can still be finite and, thus, norm of the inverse can be
+*>                computed as a strictly positive number.
 *>          = 1:  RCOND = NaN.
 *> \endverbatim
 *
@@ -194,7 +199,7 @@ SUBROUTINE SGECON( NORM, N, A, LDA, ANORM, RCOND, WORK, IWORK,
          RETURN
       ELSE IF( SISNAN( ANORM ) ) THEN
          RCOND = ANORM
-         INFO = 1
+         INFO = -5
          RETURN
       END IF
 *
@@ -252,8 +257,7 @@ SUBROUTINE SGECON( NORM, N, A, LDA, ANORM, RCOND, WORK, IWORK,
 *
 *     Compute the estimate of the reciprocal condition number.
 *
-      IF( AINVNM.NE.ZERO )
-     $   RCOND = ( ONE / AINVNM ) / ANORM
+      RCOND = ( ONE / AINVNM ) / ANORM
 *
 *     Check for NaNs
 *

diff --git a/SRC/zgecon.f b/SRC/zgecon.f
@@ -105,7 +105,12 @@
 *> \verbatim
 *>          INFO is INTEGER
 *>          = 0:  successful exit
-*>          < 0:  if INFO = -i, the i-th argument had an illegal value
+*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
+*>                NaNs are illegal values for ANORM, and they propagate to
+*>                the output parameter RCOND.
+*>                Infinity values are valid inputs for ANORM, because the values
+*>                in A can still be finite and, thus, norm of the inverse can be
+*>                computed as a strictly positive number.
 *>          = 1:  RCOND = NaN.
 *> \endverbatim
 *
@@ -201,7 +206,7 @@ SUBROUTINE ZGECON( NORM, N, A, LDA, ANORM, RCOND, WORK, RWORK,
          RETURN
       ELSE IF( DISNAN( ANORM ) ) THEN
          RCOND = ANORM
-         INFO = 1
+         INFO = -5
          RETURN
       END IF
 *
@@ -260,8 +265,7 @@ SUBROUTINE ZGECON( NORM, N, A, LDA, ANORM, RCOND, WORK, RWORK,
 *
 *     Compute the estimate of the reciprocal condition number.
 *
-      IF( AINVNM.NE.ZERO )
-     $   RCOND = ( ONE / AINVNM ) / ANORM
+      RCOND = ( ONE / AINVNM ) / ANORM
 *
 *     Check for NaNs
 *