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function [spec_out] = SplineRaw(wls_in, spec_in, wls_out, extend)
% [spec_out] = SplineRaw(wls_in, spec_in, wls_out, [extend])
%
% Convert the wavelength representation of a spectrum.
%
% Handling of out of range values:
% extend == 0: Cubic spline, extends with zeros [default]
% extend == 1: Cubic spline, extends with last value in that direction
% extend == 2: Linear interpolation, linear extrapolation
%
% spec_in may have multiple columns, in which case spec_out does as well.
%
% wls_in and wls_out may be specified as a column vector of
% wavelengths or as a [start delta num] description.
%
% 7/26/03 dhb Add extend argument
% 8/13/11 dhb Added linear extrapolation option for extend
% Default value for extend
if (nargin < 4 || isempty(extend))
extend = 0;
end
% Convert wls_in wls_out to lists if necessary
wls_in = MakeItWls(wls_in);
wls_out = MakeItWls(wls_out);
% Spline the whole enchilada
[null,n] = size(spec_in);
[m,null] = size(wls_out);
spec_out = zeros(m,n);
% I decided not to touch the way things were
% handled for extend == 0,1
switch (extend)
case {0,1}
% Check on
for i=1:n
spec_out(:,i) = spline(wls_in,spec_in(:,i),wls_out);
end
% Find range of input spectrum
min_wl = min(wls_in);
max_wl = max(wls_in);
% Truncate to zero outsize of critical range
if (extend)
index = find( wls_out < min_wl);
if (~isempty(index))
for i=1:n
spec_out(index,i) = spec_in(1,i);
end
end
index = find(wls_out > max_wl);
if (~isempty(index))
for i=1:n
spec_out(index,i) = spec_in(end,i);
end
end
else
index = find( wls_out < min_wl | wls_out > max_wl );
if (length(index) ~= 0)
spec_out(index,:) = zeros(length(index),n);
end
end
case 2,
for i=1:n
spec_out(:,i) = interp1(wls_in,spec_in(:,i),wls_out,'linear','extrap');
end
otherwise
error('Bad value passed for extend argument');
end
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