% [up,down] = findintercept(Yin), detects the intercept with signal Yin
% Options: 'Threshold','MinGradient','InterceptWidthRange',...
% 'MinInterceptDistance','MinInterceptAvarage','MinPeakHeight'
% followed by a number and Method: 'Linear','Nearest'
%
% 'Threshold': Gives the intercept with Yin
% 'MinSlope': The slope calculated from the first neighbour peak to
% neighbour valley. Supports both single value and range.
% 'InterceptWidthRange': Minimal and maximal width between intercepting points.
% Supports both single value and range. Starts with first up or down. To
% force a start use 'StartPair'.
% 'MinInterceptDistance': Distance between intercept points of either downward
% or upward intercepts.
% 'MinInterceptAvarage': Avarage over points above or under the intercept.
% Supports both single value and two values for averages above and below threshold.
% 'StartPair': 0,'Up','Down','First'_ forces starting with an
% upward or downward slope. By default it will start without any
% pre-settings (0);
% 'NIntercepts': specifies the maximum number of intercepts
%
%
% Optional output:
% no output = figure with results
% varargout{1} = Av; %Average between intercept points
% varargout{2} = slope; %Slope of intercepting point
% varargout{3} = x; %x after interpolation
% varargout{4} = Yin; %Y after interpolation
%
% Ben van Oeveren, 19-03-2016: added startPair: 0 as default