Fixes #92: xLASWP: bug for negative INCX

Thanks to Vladimír Chalupecký for noticing quite an old bug in xLASWP.  The bug
is fixed now. The cases for INCX = 1 and INCX = -1 were correct.  It is not
clear whether any other cases would be useful. So the bug was never detected.
We might want to consider to (1) forbid any values for INCX but INCX = 1 and
INCX = -1, (2) and simplify the code and the subroutine description
accordingly. Comments welcome. Julien.

diff --git a/SRC/claswp.f b/SRC/claswp.f
index 7c34778..bdafc0b 100644 (file)
--- a/SRC/claswp.f
+++ b/SRC/claswp.f
@@ -71,15 +71,15 @@
 *> \param[in] K2
 *> \verbatim
 *>          K2 is INTEGER
-*>          The last element of IPIV for which a row interchange will
-*>          be done.
+*>          (K2-K1+1) is the number of elements of IPIV for which a row
+*>          interchange will be done.
 *> \endverbatim
 *>
 *> \param[in] IPIV
 *> \verbatim
-*>          IPIV is INTEGER array, dimension (K2*abs(INCX))
-*>          The vector of pivot indices.  Only the elements in positions
-*>          K1 through K2 of IPIV are accessed.
+*>          IPIV is INTEGER array, dimension (K1+(K2-K1)*abs(INCX))
+*>          The vector of pivot indices. Only the elements in positions
+*>          K1 through K1+(K2-K1)*INCX of IPIV are accessed.
 *>          IPIV(K) = L implies rows K and L are to be interchanged.
 *> \endverbatim
 *>
@@ -143,7 +143,7 @@
          I2 = K2
          INC = 1
       ELSE IF( INCX.LT.0 ) THEN
-         IX0 = 1 + ( 1-K2 )*INCX
+         IX0 = K1 + ( K1-K2 )*INCX
          I1 = K2
          I2 = K1
          INC = -1

diff --git a/SRC/dlaswp.f b/SRC/dlaswp.f
index 1f050db..4e4d3d9 100644 (file)
--- a/SRC/dlaswp.f
+++ b/SRC/dlaswp.f
@@ -71,15 +71,15 @@
 *> \param[in] K2
 *> \verbatim
 *>          K2 is INTEGER
-*>          The last element of IPIV for which a row interchange will
-*>          be done.
+*>          (K2-K1+1) is the number of elements of IPIV for which a row
+*>          interchange will be done.
 *> \endverbatim
 *>
 *> \param[in] IPIV
 *> \verbatim
-*>          IPIV is INTEGER array, dimension (K2*abs(INCX))
-*>          The vector of pivot indices.  Only the elements in positions
-*>          K1 through K2 of IPIV are accessed.
+*>          IPIV is INTEGER array, dimension (K1+(K2-K1)*abs(INCX))
+*>          The vector of pivot indices. Only the elements in positions
+*>          K1 through K1+(K2-K1)*INCX of IPIV are accessed.
 *>          IPIV(K) = L implies rows K and L are to be interchanged.
 *> \endverbatim
 *>
@@ -143,7 +143,7 @@
          I2 = K2
          INC = 1
       ELSE IF( INCX.LT.0 ) THEN
-         IX0 = 1 + ( 1-K2 )*INCX
+         IX0 = K1 + ( K1-K2 )*INCX
          I1 = K2
          I2 = K1
          INC = -1

diff --git a/SRC/slaswp.f b/SRC/slaswp.f
index 5ea247b..f3a16ff 100644 (file)
--- a/SRC/slaswp.f
+++ b/SRC/slaswp.f
@@ -71,15 +71,15 @@
 *> \param[in] K2
 *> \verbatim
 *>          K2 is INTEGER
-*>          The last element of IPIV for which a row interchange will
-*>          be done.
+*>          (K2-K1+1) is the number of elements of IPIV for which a row
+*>          interchange will be done.
 *> \endverbatim
 *>
 *> \param[in] IPIV
 *> \verbatim
-*>          IPIV is INTEGER array, dimension (K2*abs(INCX))
-*>          The vector of pivot indices.  Only the elements in positions
-*>          K1 through K2 of IPIV are accessed.
+*>          IPIV is INTEGER array, dimension (K1+(K2-K1)*abs(INCX))
+*>          The vector of pivot indices. Only the elements in positions
+*>          K1 through K1+(K2-K1)*INCX of IPIV are accessed.
 *>          IPIV(K) = L implies rows K and L are to be interchanged.
 *> \endverbatim
 *>
@@ -143,7 +143,7 @@
          I2 = K2
          INC = 1
       ELSE IF( INCX.LT.0 ) THEN
-         IX0 = 1 + ( 1-K2 )*INCX
+         IX0 = K1 + ( K1-K2 )*INCX
          I1 = K2
          I2 = K1
          INC = -1

diff --git a/SRC/zlaswp.f b/SRC/zlaswp.f
index 82244ef..b695d94 100644 (file)
--- a/SRC/zlaswp.f
+++ b/SRC/zlaswp.f
@@ -71,15 +71,15 @@
 *> \param[in] K2
 *> \verbatim
 *>          K2 is INTEGER
-*>          The last element of IPIV for which a row interchange will
-*>          be done.
+*>          (K2-K1+1) is the number of elements of IPIV for which a row
+*>          interchange will be done.
 *> \endverbatim
 *>
 *> \param[in] IPIV
 *> \verbatim
-*>          IPIV is INTEGER array, dimension (K2*abs(INCX))
-*>          The vector of pivot indices.  Only the elements in positions
-*>          K1 through K2 of IPIV are accessed.
+*>          IPIV is INTEGER array, dimension (K1+(K2-K1)*abs(INCX))
+*>          The vector of pivot indices. Only the elements in positions
+*>          K1 through K1+(K2-K1)*INCX of IPIV are accessed.
 *>          IPIV(K) = L implies rows K and L are to be interchanged.
 *> \endverbatim
 *>
@@ -143,7 +143,7 @@
          I2 = K2
          INC = 1
       ELSE IF( INCX.LT.0 ) THEN
-         IX0 = 1 + ( 1-K2 )*INCX
+         IX0 = K1 + ( K1-K2 )*INCX
          I1 = K2
          I2 = K1
          INC = -1