time   calls  line
                  1 function [x,y,sizey,endslopes] = chckxy(x,y)
                  2 %CHCKXY check and adjust input for SPLINE and PCHIP
                  3 %   [X,Y,SIZEY] = CHCKXY(X,Y) checks the data sites X and corresponding data
                  4 %   values Y, making certain that there are exactly as many sites as values,
                  5 %   that no two data sites are the same, removing any data points that involve 
                  6 %   NaNs, reordering the sites if necessary to ensure that X is a strictly
                  7 %   increasing row vector and reordering the data values correspondingly,
                  8 %   and reshaping Y if necessary to make sure that it is a matrix, with Y(:,j)
                  9 %   the data value corresponding to the data site X(j), and with SIZEY the
                 10 %   actual dimensions of the given values. 
                 11 %   This call to CHCKXY is suitable for PCHIP.
                 12 %
                 13 %   [X,Y,SIZEY,ENDSLOPES] = CHCKXY(X,Y) also considers the possibility that
                 14 %   there are two more data values than there are data sites.
                 15 %   If there are, then the first and the last data value are removed from Y
                 16 %   and returned separately as ENDSLOPES. Otherwise, an empty ENDSLOPES is
                 17 %   returned.  This call to CHCKXY is suitable for SPLINE.
                 18 %
                 19 %   See also PCHIP, SPLINE.
                 20 
                 21 %   Copyright 1984-2003 The MathWorks, Inc.
                 22 
                 23 % make sure X is a vector:
            25   24 if length(find(size(x)>1))>1  
                 25   error(message('MATLAB:chckxy:XNotVector')) 
                 26 end
                 27 
                 28 % ensure X is real
            25   29 if any(~isreal(x))  
                 30   error(message('MATLAB:chckxy:XComplex')) 
                 31 end
                 32 
                 33 % deal with NaN's among the sites:
  0.01      25   34 nanx = find(isnan(x)); 
  0.01      25   35 if ~isempty(nanx) 
                 36    x(nanx) = [];
                 37    warning(message('MATLAB:chckxy:nan'))
                 38 end
                 39 
            25   40 n=length(x); 
            25   41 if n<2  
                 42   error(message('MATLAB:chckxy:NotEnoughPts')) 
                 43 end
                 44 
                 45 % re-sort, if needed, to ensure strictly increasing site sequence:
            25   46 x=x(:).';  
            25   47 dx = diff(x); 
                 48 
  0.01      25   49 if any(dx<0), [x,ind] = sort(x); dx = diff(x); else ind=1:n; end 
                 50 
            25   51 if ~all(dx), error(message('MATLAB:chckxy:RepeatedSites')), end 
                 52 
                 53 % if Y is ND, reshape it to a matrix by combining all dimensions but the last:
            25   54 sizey = size(y); 
                 55 
                 56 
            25   57 while length(sizey)>2&&sizey(end)==1, sizey(end) = []; end 
                 58 
                 59 
            25   60 yn = sizey(end);  
            25   61 sizey(end)=[];  
            25   62 yd = prod(sizey); 
                 63 
            25   64 if length(sizey)>1 
                 65    y = reshape(y,yd,yn);
            25   66 else 
                 67    % if Y happens to be a column matrix, change it to the expected row matrix.
            25   68    if yn==1 
                 69        yn = yd;
                 70        y = reshape(y,1,yn); 
                 71        yd = 1; 
                 72        sizey = yd;
                 73    end
            25   74 end 
                 75 
                 76 % determine whether not-a-knot or clamped end conditions are to be used:
            25   77 nstart = n+length(nanx); 
            25   78 if yn==nstart 
            25   79    endslopes = []; 
                 80 elseif nargout==4&&yn==nstart+2
                 81    endslopes = y(:,[1 n+2]); y(:,[1 n+2])=[];
                 82    if any(isnan(endslopes))
                 83       error(message('MATLAB:chckxy:EndslopeNaN'))
                 84    end
                 85    if any(isinf(endslopes))
                 86        error(message('MATLAB:chckxy:EndslopeInf'))
                 87    end
                 88 else
                 89    error('MATLAB:chckxy:NumSitesMismatchValues',...
                 90         ['The number of sites, ' int2str(nstart), ...
                 91         ', is incompatible with the number of values, ' int2str(yn) '.'])
                 92 end
                 93 
                 94 % deal with NaN's among the values:
            25   95 if ~isempty(nanx) 
                 96     y(:,nanx) = [];
                 97 end
                 98 
            25   99 y=y(:,ind); 
            25  100 nany = find(sum(isnan(y),1)); 
            25  101 if ~isempty(nany) 
                102    y(:,nany) = []; x(nany) = [];
                103    warning(message('MATLAB:chckxy:IgnoreNaN'))
                104    n = length(x);
                105    if n<2 
                106      error(message('MATLAB:chckxy:NotEnoughPts')) 
                107    end
                108 end

Other subfunctions in this file are not included in this listing.