SURRGT3A.DOG

function yrev=surrgt3a(x,y,yr,yrc);
%
% Compute surrogate data for part of one time series, given overlap
% data for that series with another.  Called by surrgt2.m
%
% Meko 2-21-97
%
% 
%******************IN
%
% x(mx x 1)r one time series
% y(my x 1)r another series, needing estimate
% yr (m1 x 1)i year vector for x, y
% yrc (m2 x 1)i year vector for calibration period.  Any data in this
%   period that is NaN in y will be replaced with estimated data
%		based on stdzd anomalies using stats from overlap of x and y
%
%******************* OUT
%
% yrev (my x 1)r revised y
%
%**************** CALLS
%
% scale1.m
%
%******************** NOTES ******************************
%
% Uses method described in scale1.m
% Dedicated function for surrgt2.m
%


[mx,nx]=size(x);
[my,ny]=size(y);
if mx ~=my;
	error('x and y must be same length');
end
if nx~=1 | ny~=1;
	error('x and y must be col vects');
end


% Get overlap segments of x,y
L1=~isnan(x) & ~isnan(y);
x1=x(L1);
y1=y(L1);


% Make pointer to part of calib period needing data for y
yrgo=yrc(1);
yrsp=yrc(length(yrc));
L2=yr>=yrgo & yr<=yrsp & isnan(y);

% Get that data for x, and check that no NaN in this data
x2=x(L2);
if any(isnan(x2)); 
	error('NaN in the predictor series x2 in calib period');
end

% Call scale1.m to get estimated data for that period in y
y2=scale1(x1,y1,x2);


%  Substitute the estimates in y
y(L2)=y2;
yrev = y;