timetick(ax,precision)

function timetick(ax,precision)
% TIMETICK    Time formatted tick labels
%
% TIMETICK sets current axes to time formatted tick labels.
% X Axis must be time, in datenum format
%
% TIMETICK(AX) sets axes with handle AX to time formatted tick labels
%
% TIMETICK(AX,precision) sets axes with handle AX to time formatted tick
% labels with precision values to the right of the decimal for seconds
% specifier

% Scott Hirsch
% The MathWorks
% Copyright 2003 The MathWorks, Inc

% Default - use GCA
if nargin==0 || isempty(ax) || ax ==0
    ax = gca;
end;

if nargin<2
    precision = 4;
end;

% Get tick values
xt = get(ax,'XTick');

% Convert to time string
xtl = timestr(xt,precision);

% Set ticks to the time string
set(ax,'XTickLabel',xtl);

function S = timestr(D,precision)
%timestr          String representation of time.   HH:MM:SS.SSSS
%
% TIMESTR(D) converts D, a serial date number (as returned by DATENUM)
% into a time string with the format HH:MM:SS.SSSS
%
% TIMESTR(D,precision) uses precision values to the right of the decimal

if nargin==1
    precision=4;
end;

if precision > 0
    totalwidth = precision + 3;   %2 to left of decimal, plus decimal
else
    totalwidth = 2;               %2 to left of decimal (decimal won't display)

end
precision = num2str(precision);
totalwidth = num2str(totalwidth);

D = D(:);

% Obtain components of date number
[y,mo,d,h,min,s] = datevecmx(D,1.1);  mo(mo==0) = 1;

% Generate formatted string
% sw = floor(s);      %Whole
% sf = floor((s-sw)*1000);          %Fraction
% M = [h';min';sw';sf'];       %sprintf works columnwise
% fmt = '%02d:%02d:%02d.%04d';
M = [h';min';s'];       %sprintf works columnwise

% Figure out how long to make seconds format.
% Since we are building a string array, every element must be the same
% length
sw = floor(s);      %Whole
sf = floor((s-sw)*1000);          %Fraction

fmt = ['%02d:%02d:%0' totalwidth '.' precision 'f'];
S = sprintf(fmt,M(:,1));
for ii=2:length(D)
    t= sprintf(fmt,M(:,ii));
    S = [S;t];
end;

% My formatting is a bit messed up.  I can't figure out how to add
% zeros when necessary for seconds - I end up with blanks.
% Replace blanks with 0
% blnks = find(double(S)==32);        % 32 - ASCII for 0
% S(blnks) = '0';