quickplot.m

Matlab源程序

function quickplot(fun,xlim)
%QUICKPLOT Generate quick plot of a function
% Function QUICKPLOT generates a quick plot 
% of a function contained in a external m-file,
% between user-specified x limits.
 
% Define variables:
%   fun       -- Function to plot
%   msg       -- Error message
%   n_steps   -- Number of steps to plot
%   step_size -- Step size
%   x         -- X-values to plot
%   y         -- Y-values to plot
%   xlim      -- Plot x limits

%  Record of revisions:
%      Date       Programmer          Description of change
%      ====       ==========          =====================
%    12/17/98    S. J. Chapman        Original code

% Check for a legal number of input arguments.
msg = nargchk(2,2,nargin);
error(msg);

% Check the second argument to see if it has two 
% elements.  Note that this double test allows the 
% argument to be either a row or a column vector.
if ( size(xlim,1) == 1 & size(xlim,2) == 2 ) | ...
   ( size(xlim,1) == 2 & size(xlim,2) == 1 )
   
   % Ok--continue processing.
   n_steps = 100;
   step_size = (xlim(2) - xlim(1)) / n_steps;
   x = xlim(1):step_size:xlim(2);
   y = feval(fun,x);
   plot(x,y);
   title(['\bfPlot of function ' fun '(x)']);
   xlabel('\bfx');
   ylabel(['\bf' fun '(x)']);
   
else
   % Else wrong number of elements in xlim.
   error('Incorrect number of elements in xlim.');
end