lapack: imported lapack as a subtree

lapack/internal/testdata/netlib/dnrm2.f

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+*> \brief \b DNRM2
+*
+*  =========== DOCUMENTATION ===========
+*
+* Online html documentation available at 
+*            http://www.netlib.org/lapack/explore-html/ 
+*
+*  Definition:
+*  ===========
+*
+*       DOUBLE PRECISION FUNCTION DNRM2(N,X,INCX)
+* 
+*       .. Scalar Arguments ..
+*       INTEGER INCX,N
+*       ..
+*       .. Array Arguments ..
+*       DOUBLE PRECISION X(*)
+*       ..
+*  
+*
+*> \par Purpose:
+*  =============
+*>
+*> \verbatim
+*>
+*> DNRM2 returns the euclidean norm of a vector via the function
+*> name, so that
+*>
+*>    DNRM2 := sqrt( x'*x )
+*> \endverbatim
+*
+*  Authors:
+*  ========
+*
+*> \author Univ. of Tennessee 
+*> \author Univ. of California Berkeley 
+*> \author Univ. of Colorado Denver 
+*> \author NAG Ltd. 
+*
+*> \date November 2011
+*
+*> \ingroup double_blas_level1
+*
+*> \par Further Details:
+*  =====================
+*>
+*> \verbatim
+*>
+*>  -- This version written on 25-October-1982.
+*>     Modified on 14-October-1993 to inline the call to DLASSQ.
+*>     Sven Hammarling, Nag Ltd.
+*> \endverbatim
+*>
+*  =====================================================================
+      DOUBLE PRECISION FUNCTION DNRM2(N,X,INCX)
+*
+*  -- Reference BLAS level1 routine (version 3.4.0) --
+*  -- Reference BLAS is a software package provided by Univ. of Tennessee,    --
+*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
+*     November 2011
+*
+*     .. Scalar Arguments ..
+      INTEGER INCX,N
+*     ..
+*     .. Array Arguments ..
+      DOUBLE PRECISION X(*)
+*     ..
+*
+*  =====================================================================
+*
+*     .. Parameters ..
+      DOUBLE PRECISION ONE,ZERO
+      PARAMETER (ONE=1.0D+0,ZERO=0.0D+0)
+*     ..
+*     .. Local Scalars ..
+      DOUBLE PRECISION ABSXI,NORM,SCALE,SSQ
+      INTEGER IX
+*     ..
+*     .. Intrinsic Functions ..
+      INTRINSIC ABS,SQRT
+*     ..
+      IF (N.LT.1 .OR. INCX.LT.1) THEN
+          NORM = ZERO
+      ELSE IF (N.EQ.1) THEN
+          NORM = ABS(X(1))
+      ELSE
+          SCALE = ZERO
+          SSQ = ONE
+*        The following loop is equivalent to this call to the LAPACK
+*        auxiliary routine:
+*        CALL DLASSQ( N, X, INCX, SCALE, SSQ )
+*
+          DO 10 IX = 1,1 + (N-1)*INCX,INCX
+              IF (X(IX).NE.ZERO) THEN
+                  ABSXI = ABS(X(IX))
+                  IF (SCALE.LT.ABSXI) THEN
+                      SSQ = ONE + SSQ* (SCALE/ABSXI)**2
+                      SCALE = ABSXI
+                  ELSE
+                      SSQ = SSQ + (ABSXI/SCALE)**2
+                  END IF
+              END IF
+   10     CONTINUE
+          NORM = SCALE*SQRT(SSQ)
+      END IF
+*
+      DNRM2 = NORM
+      RETURN
+*
+*     End of DNRM2.
+*
+      END