% EXTRACT - Extract a section from an input vector which contains an 
%           n-dimensional array in a linear series.
%           Usage: out = Extract( InputVector, section )
%           InputVector is of form
%           [ NumberDimensions Dim1 Dim2 ... DimN data ]
%           section is of form
%           [ Dim1Min Dim1Max Dim2Min Dim2Max ... DimNMin DimNMax ]
%
function outArr = Extract( inArr, subSection )
if nargin ~= 2 
  fprintf(2,'**ERROR** wrong number of arguments.\n')
  fprintf(2,'Usage: a = Slice ( b, [ xmin xmax ymin ymax ... ]\n')
  return
end
if size(subSection,1) ~= 1
  fprintf(2,'**ERROR** sub-section incorrectly specified.\n')
  fprintf(2,'Usage: a = Slice ( b, [ xmin xmax ymin ymax ... ]\n')
  return
end
if inArr(1)*2 ~= size(subSection,2)
  fprintf(2,'**ERROR** sub-section has wrong number of elments.\n')
  fprintf(2,'Usage: a = Slice ( b, [ xmin xmax ymin ymax ... ]\n')
  return
end
%
% Get dimensions of data array help in input vector.
nD=inArr(1);                                
Ds=inArr(2:nD+1);
for i=1:nD
 s1(i)=subSection((i-1)*2+1); s2(i)=subSection((i-1)*2+2);
end
inStep(1)=1;
for i=2:nD
  inStep(i)=inStep(i-1)*Ds(i-1);
end
nC=1;
for i =1:nD
  nC=nC*(subSection((i-1)*2+2)-subSection((i-1)*2+1)+1);
end
wk=zeros(nC,nD);
%
%  Build list of coordinates to extract.
for i=1:nD                   
 ss=subSection((i-1)*2+1); se=subSection((i-1)*2+2);
 if i == 1 lCycle = 1;
 else      lCycle = prod((s2(1:i-1)-s1(1:i-1)+1));
 end
 if i < nD nRep = prod((s2(i+1:nD)-s1(i+1:nD)+1));
 else      nRep = 1;
 end
 blk=reshape(([ss:se]'*(zeros(1,lCycle)+1))',lCycle*(se-ss+1),1);
 wk(:,i)=reshape(blk*(zeros(1,nRep)+1),nRep*lCycle*(se-ss+1),1);
end
%
% Translate coordinate list into offsets along vector.
iS=[0,inStep(2:nD)];                          
wk(:,1)=1+nD+wk(:,1)+(wk-1)*iS';
%
% Extract selected locations.
outArr=inArr(wk(:,1)');                        
return