matlab_class/gcmfaces_calc/gcmfaces_interp_1d.m

function [Vq]=gcmfaces_interp_1d(xDim,X,V,Xq);
%[Vq]=GCMFACES_INTERP_1D(xDim,X,V,Xq);
%  Linearly interpolates a field (V; array or gcmfaces) along a 
%  selected dimension (xDim) from locations specified in 
%  vector X to locations specified in vector Xq 

gcmfaces_global;

%change format if needed
isagcmfaces=isa(V,'gcmfaces');
if isagcmfaces; V=convert2gcmfaces(V); end;

%move interpolation dimension to first
ndim=length(size(V));
tmp1=circshift([1:ndim],[0 1-xDim]);
V=permute(V,tmp1);
if size(X,1)==1; X=X'; end;
if size(Xq,1)==1; Xq=Xq'; end;

%the interpolation itself
Kq=interp1(X,[1:length(X)]',Xq,'linear');
Kqne=interp1(X,[1:length(X)]',Xq,'nearest','extrap');

%use bilinear; then extrapolate with nearest neighbor 
Vq=NaN*repmat(V(1,:,:),[length(Xq) 1 1]);
for kk=1:length(Xq);
    if ~isnan(Kq(kk));
        k0=floor(Kq(kk));
        k1=min(k0+1,length(X));
        a0=Kq(kk)-k0;
        tmp1=(1-a0)*V(k0,:,:)+a0*V(k1,:,:);
    else;
        tmp1=NaN*V(1,:,:);
    end;
    tmp2=V(Kqne(kk),:,:);
    tmp1(isnan(tmp1))=tmp2(isnan(tmp1));
    Vq(kk,:,:)=tmp1;
end;

%move interpolation dimension to first
tmp1=circshift([1:ndim],[0 xDim-1]);
Vq=permute(Vq,tmp1);

%change format if needed
if isagcmfaces; Vq=convert2gcmfaces(Vq); end;

1	function [Vq]=gcmfaces_interp_1d(xDim,X,V,Xq);
2	%[Vq]=GCMFACES_INTERP_1D(xDim,X,V,Xq);
3	% Linearly interpolates a field (V; array or gcmfaces) along a
4	% selected dimension (xDim) from locations specified in
5	% vector X to locations specified in vector Xq
6
7	gcmfaces_global;
8
9	%change format if needed
10	isagcmfaces=isa(V,'gcmfaces');
11	if isagcmfaces; V=convert2gcmfaces(V); end;
12
13	%move interpolation dimension to first
14	ndim=length(size(V));
15	tmp1=circshift([1:ndim],[0 1-xDim]);
16	V=permute(V,tmp1);
17	if size(X,1)==1; X=X'; end;
18	if size(Xq,1)==1; Xq=Xq'; end;
19
20	%the interpolation itself
21	Kq=interp1(X,[1:length(X)]',Xq,'linear');
22	Kqne=interp1(X,[1:length(X)]',Xq,'nearest','extrap');
23
24	%use bilinear; then extrapolate with nearest neighbor
25	Vq=NaN*repmat(V(1,:,:),[length(Xq) 1 1]);
26	for kk=1:length(Xq);
27	if ~isnan(Kq(kk));
28	k0=floor(Kq(kk));
29	k1=min(k0+1,length(X));
30	a0=Kq(kk)-k0;
31	tmp1=(1-a0)V(k0,:,:)+a0V(k1,:,:);
32	else;
33	tmp1=NaN*V(1,:,:);
34	end;
35	tmp2=V(Kqne(kk),:,:);
36	tmp1(isnan(tmp1))=tmp2(isnan(tmp1));
37	Vq(kk,:,:)=tmp1;
38	end;
39
40	%move interpolation dimension to first
41	tmp1=circshift([1:ndim],[0 xDim-1]);
42	Vq=permute(Vq,tmp1);
43
44	%change format if needed
45	if isagcmfaces; Vq=convert2gcmfaces(Vq); end;
46