LinkTopAxisData (TopTickPositions,TopTickLabels,AxisName)

function [newAxis] = LinkTopAxisData (TopTickPositions,TopTickLabels,AxisName)
% [newAxis] = LinkTopAxisData (TopTickPositions,TopTickLabels,AxisName)
%
% TopTickPositions specifies the position of the ticks for the top x axis in
% the units of the bottom axis.
%
% TopTickLabels specifies the numerical label for these ticks
%
% AxisName is optional, but if specified it will label the new X axis
%
% newAxis is a handle to the newly created axis
%
% Example (Arrhenius plot with temperature as a top scale):
% T=300:-10:100;E=exp(1./T); % Define a dummy set of data
% figure;plot(1000./T,E);xlabel('1000/T / K^{-1}') % Plot the data
% LinkTopAxisData(1000./(300:-50:100),300:-50:100,'T / K'); % Add a top axis
%
% The function will create the new axis behind the current one, so
% clicking gives the original axis rather than the new (dummy) one.
% The properties of the new axis are also linked to the old one, so zooming
% and rescaling should work as advertised.  It will even handle changes to
% linear / log etc.
%
% The (known) bugs are:
%
%  1) On a y log scale where one of the limits is zero the tick marks won't
%  quite align - this is because Matlab reports the lower limit as zero
%  even though it displays a non zero lower limit
%
%  2) Because the two axes are linked, the autoscale checkbox doesn't work
%  for the x and y limits.
%
%  This code is based on the addTopXAxis code by Emmanuel P. Dinnat
%  which can be found on the Matlab file exchange.  The main differences
%  between his program and this one are
%
%  1) This code inputs the top ticks as an array, and they don't have to
%  correspond to the tick positions on the bottom axis
%
%  2) This code hides the new axis behind the first one (making clicking
%  more intuitive)
%
%  3) However... this code is less powerful.


    temp=[TopTickPositions; TopTickLabels];
    temp=real(temp);
    %temp=temp(:,temp(2,:)<0);
    temp=sortrows(temp');
    temp=temp(diff(temp(:,1))>0,:);
    

    oldAxis=gca;
    % Shift up the title a bit
    set(get(oldAxis,'Title'),'Units','Normalized','Position',[0.5 1.05 0]);
    % Create new axis
    newAxis = axes('position', get(oldAxis, 'position'));
    % put new Xaxis on top
	set(newAxis, 'xaxisLocation', 'top');
    set(oldAxis, 'xaxislocation', 'bottom');
    % Make the new one the colour of the old, and the old transparent
    set(newAxis,'Color',get(oldAxis,'Color'));
    set(oldAxis,'Color','none');
    % Give the new axis a name if necessary
    if nargin==3;xlabel(AxisName);end;
    
    % Get rid of y labels on the new axis
	set(newAxis, 'yTickLabel', []);
	% remove box for old axis
	set(oldAxis, 'box', 'off');
	% remove grids
	set(newAxis, 'yGrid', 'off');
	set(newAxis, 'xGrid', 'off');
    % simulate the presence of a box by making the new axis' y axis appear
    % on the right whilst the old one sits on the left
    set(newAxis, 'YAxisLocation', 'right');
    set(oldAxis, 'YAxisLocation', 'left');
    
    set(newAxis, 'YScale', get(oldAxis, 'YScale'));
    set(newAxis, 'YTick', get(oldAxis, 'YTick'));
    set(newAxis, 'XScale', get(oldAxis, 'XScale'));
    set(newAxis, 'XTick', get(oldAxis, 'XTick'));

    linkaxes([oldAxis newAxis],'xy');
    % Create a link between properties
    hlink = linkprop([newAxis, oldAxis], {'Position','YTick','XScale','YScale','YMinorTick'});
    % And store it on the new axis (to make sure it gets updated, but is
    % also destroyed when the figure is closed / axis is deleted)
    setappdata(newAxis,'Axis_Linkage',hlink);
    
    % Label the new axis bits
    set(newAxis,'XTick',temp(:,1));
    set(newAxis,'XTickLabel',num2str(temp(:,2)));
    
    % and finally, swap the places of the two axes so that clicking gives the correct
    % behaviour
    temp=get(gcf,'Children');
    i=temp==newAxis;
    j=temp==oldAxis;
    temp(i)=oldAxis;
    temp(j)=newAxis;
    
    set(gcf,'Children',temp);
    
    axis(oldAxis);