[n,dx,incx,dy,incy,dparam]=drotm(n,dx,incx,dy,incy,dparam);

function [n,dx,incx,dy,incy,dparam]=drotm(n,dx,incx,dy,incy,dparam);
persistent dflag dh11 dh12 dh21 dh22 firstCall i kx ky nsteps two w z zero ; if isempty(firstCall),firstCall=1;end; 

if isempty(i), i=0; end;
if isempty(kx), kx=0; end;
if isempty(ky), ky=0; end;
if isempty(nsteps), nsteps=0; end;
%***BEGIN PROLOGUE  DROTM
%***PURPOSE  Apply a modified Givens transformation.
%***LIBRARY   SLATEC (BLAS)
%***CATEGORY  D1A8
%***TYPE      doubleprecision (SROTM-S, DROTM-D)
%***KEYWORDS  BLAS, LINEAR ALGEBRA, MODIFIED GIVENS ROTATION, VECTOR
%***AUTHOR  Lawson, C. L., (JPL)
%           Hanson, R. J., (SNLA)
%           Kincaid, D. R., (U. of Texas)
%           Krogh, F. T., (JPL)
%***DESCRIPTION
%
%                B L A S  Subprogram
%    Description of Parameters
%
%     --Input--
%        N  number of elements in input vector(s)
%       DX  doubleprecision vector with N elements
%     INCX  storage spacing between elements of DX
%       DY  doubleprecision vector with N elements
%     INCY  storage spacing between elements of DY
%   DPARAM  5-element D.P. vector.  DPARAM(1) is DFLAG described below.
%           Locations 2-5 of SPARAM contain elements of the
%           transformation matrix H described below.
%
%     --Output--
%       DX  rotated vector (unchanged if N .LE. 0)
%       DY  rotated vector (unchanged if N .LE. 0)
%
%     Apply the modified Givens transformation, H, to the 2 by N matrix
%     (DX**T)
%     (DY**T) , where **T indicates transpose.  The elements of DX are
%     in DX(LX+I*INCX), I = 0 to N-1, where LX = 1 if INCX .GE. 0, else
%     LX = 1+(1-N)*INCX, and similarly for DY using LY and INCY.
%
%     With DPARAM(1)=DFLAG, H has one of the following forms:
%
%     DFLAG=-1.0D0     DFLAG=0.0D0        DFLAG=1.0D0     DFLAG=-2.0D0
%
%       (DH11  DH12)    (1.0D0  DH12)    (DH11  1.0D0)    (1.0D0  0.0D0)
%     H=(          )    (          )    (          )    (          )
%       (DH21  DH22),   (DH21  1.0D0),   (-1.0D0 DH22),   (0.0D0  1.0D0).
%
%     See DROTMG for a description of data storage in DPARAM.
%
%***REFERENCES  C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T.
%                 Krogh, Basic linear algebra subprograms for Fortran
%                 usage, Algorithm No. 539, Transactions on Mathematical
%                 Software 5, 3 (September 1979), pp. 308-323.
%***ROUTINES CALLED  (NONE)
%***REVISION HISTORY  (YYMMDD)
%   791001  DATE WRITTEN
%   861211  REVISION DATE from Version 3.2
%   891214  Prologue converted to Version 4.0 format.  (BAB)
%   920310  Corrected definition of LX in DESCRIPTION.  (WRB)
%   920501  Reformatted the REFERENCES section.  (WRB)
%***end PROLOGUE  DROTM
if isempty(dflag), dflag=0; end;
if isempty(dh12), dh12=0; end;
if isempty(dh22), dh22=0; end;
if isempty(two), two=0; end;
if isempty(z), z=0; end;
if isempty(dh11), dh11=0; end;
if isempty(dh21), dh21=0; end;
if isempty(w), w=0; end;
if isempty(zero), zero=0; end;
dx_shape=size(dx);dx=reshape(dx,1,[]);
dy_shape=size(dy);dy=reshape(dy,1,[]);
if firstCall,   zero =[0.0d0];  end;
if firstCall,  two=[2.0d0];  end;
firstCall=0;
%***FIRST EXECUTABLE STATEMENT  DROTM
dflag = dparam(1);
if( n>0 &&(dflag+two~=zero) )
if( incx~=incy || incx<=0 )
kx = 1;
ky = 1;
if( incx<0 )
kx = fix(1 +(1-n).*incx);
end;
if( incy<0 )
ky = fix(1 +(1-n).*incy);
end;
%
if( dflag<0 )
dh11 = dparam(2);
dh12 = dparam(4);
dh21 = dparam(3);
dh22 = dparam(5);
for i = 1 : n;
w = dx(kx);
z = dy(ky);
dx(kx) = w.*dh11 + z.*dh12;
dy(ky) = w.*dh21 + z.*dh22;
kx = fix(kx + incx);
ky = fix(ky + incy);
end; i = fix(n+1);
elseif( dflag==0 ) ;
dh12 = dparam(4);
dh21 = dparam(3);
for i = 1 : n;
w = dx(kx);
z = dy(ky);
dx(kx) = w + z.*dh12;
dy(ky) = w.*dh21 + z;
kx = fix(kx + incx);
ky = fix(ky + incy);
end; i = fix(n+1);
else;
dh11 = dparam(2);
dh22 = dparam(5);
for i = 1 : n;
w = dx(kx);
z = dy(ky);
dx(kx) = w.*dh11 + z;
dy(ky) = -w + dh22.*z;
kx = fix(kx + incx);
ky = fix(ky + incy);
end; i = fix(n+1);
end;
else;
%
nsteps = fix(n.*incx);
if( dflag<0 )
dh11 = dparam(2);
dh12 = dparam(4);
dh21 = dparam(3);
dh22 = dparam(5);
for i = 1 : incx: nsteps ;
w = dx(i);
z = dy(i);
dx(i) = w.*dh11 + z.*dh12;
dy(i) = w.*dh21 + z.*dh22;
end; i = fix(nsteps +1);
elseif( dflag==0 ) ;
dh12 = dparam(4);
dh21 = dparam(3);
for i = 1 : incx: nsteps ;
w = dx(i);
z = dy(i);
dx(i) = w + z.*dh12;
dy(i) = w.*dh21 + z;
end; i = fix(nsteps +1);
else;
dh11 = dparam(2);
dh22 = dparam(5);
for i = 1 : incx: nsteps ;
w = dx(i);
z = dy(i);
dx(i) = w.*dh11 + z;
dy(i) = -w + dh22.*z;
end; i = fix(nsteps +1);
end;
end;
end;
dx_shape=zeros(dx_shape);dx_shape(:)=dx(1:numel(dx_shape));dx=dx_shape;
dy_shape=zeros(dy_shape);dy_shape(:)=dy(1:numel(dy_shape));dy=dy_shape;
end
%DECK DROTMG