When you attempt to run a function by pressing the green Run button, MATLAB never, I repeat never searches the calling environment or the base workspace or the global workspace looking for variables that have the same names as the named parameters such as xord . The only way that MATLAB can know what value to use for parameters named in a function definition is if the call to the function passes in values to the parameters positionally.
x = 0:.1:1;
y = rand(size(x));
pc = '-*';
zohplot(x, y, pc)
function zohplot(xord,yord,plotchar)
% function zohplot(xord,yord,plotchar)
%
% zohplot.m Plots the zero-order hold of two columns of data. If
% yord is a matrix then it plots each column of yord vs
% the vector xord. xord and yord must have the same
% row dimension.
%
% xord = data in the x coordinate
% yord = data in the y coordinate
% plotchar = the line or point-type as in plot(x,y,'plotchar')
%
% Written 2/24/87 by Daniel Abramovitch.
%
% modified last 3/18/87 FRH
%
[xlen,xwid] = size(xord);
xlen = xlen-1;
%
% if xlen==0, then assume data was provided in row rather than
% column format and transpose input. these variables are local,
% so the change will not affect the users format.
%
if xlen==0
xord=xord';
[xlen,xwid] = size(xord);
xlen = xlen-1;
yord=yord';
end
[ylen,ywid] = size(yord);
ylen = ylen-1;
if xlen~=ylen
disp('--ERROR-- xord and yord must have same number of rows')
return
end
bigx=zeros(2*xlen,1); % Fill these with zero;
bigy=zeros(2*ylen,ywid);
txlm1 = 2*xlen-1;
txl = 2*xlen;
xlp1 = xlen+1;
bigx(1:2:txlm1) = xord(1:xlen);
bigx(2:2:txl) = xord(2:xlp1);
bigy(1:2:txlm1,:) = yord(1:xlen,:);
bigy(2:2:txl,:) = yord(1:xlen,:);
if(nargin <= 2)
plot(bigx,bigy);
else
plot(bigx,bigy,plotchar);
end
%
end
