DOUBLE PRECISION FUNCTION DNRM2( N, SX, INCX ) **************************************************************************** * * * DATA PARALLEL BLAS based on MPL * * * * Version 1.0 1/9-92 , * * For MasPar MP-1 computers * * * * para//ab, University of Bergen, NORWAY * * * * These programs must be called using F90 style array syntax. * * Note that the F77 style calling sequence has been retained * * in this version for compatibility reasons, be aware that * * parameters related to the array dimensions and shape therefore may * * be redundant and without any influence. * * The calling sequence may be changed in a future version. * * Please report any BUGs, ideas for improvement or other * * comments to * * adm@parallab.uib.no * * * * Future versions may then reflect your suggestions. * * The most current version of this software is available * * from netlib@nac.no , send the message `send index from maspar' * * * * REVISIONS: * * * **************************************************************************** implicit none * * compute the 2-norm of a vector. * written by tor sorevik, 9/25/92. * * .. Scalar Arguments .. INTEGER INCX, N * .. * .. Array Arguments .. double precision, array(:) :: SX * .. * .. Local Scalars .. INTEGER m,ix,jx * .. * .. Intrinsic Functions .. INTRINSIC dotproduct * .. * .. Executable Statements .. * DNRM2 = 0.0D0 IF( N.LE.0 ) return * * code for increment equal to 1 * IF( INCX.EQ.1 ) then dnrm2 = dotproduct(sx(1:n), sx(1:n)) else * * code for increments not equal to 1 * m = n - 1 ix = 1 jx = 1 + m * incx * if ( incx .lt. 0 ) then ix = 1 - m * incx jx = 1 endif * dnrm2 = dotproduct(sx(ix:jx:incx),sx(ix:jx:incx)) endif * * taking the squareroot and returning * dnrm2 = sqrt(dnrm2) RETURN * * End of DNRM2 . * END