How to I turn a fprintf column of values into a matrix

I have a list of values in a column from my 'fprintf' code:

fprintf ('x  \t\t y (Euler)\t y (analytical) \n') 
fprintf ('%f \t %f\t %f\n',x0,y,f(x0))

for x = x0 : h : xn-h
  y = y + dy(x,y)*h
  x = x + h
  fprintf ('%f \t %f\t %f\n',x,y,f(x))
end

This gives me a considerable number of values in a fprintf code. I however want to plot my two 'Y' values against eachother of a graph against the x value

Answer 1

[James Tursa]

You can save all the values for plotting. E.g.,

xp = x0;
yp = y;
fp = f(x0);
k = 1;
for x = x0 : h : xn-h
  y = y + dy(x,y)*h
  x = x + h
  fprintf ('%f \t %f\t %f\n',x,y,f(x))
  k = k + 1;
  xp(k) = x;
  yp(k) = y;
  fp(k) = f(x);
end

Then you can plot xp, yp, fp.

If you have a large number of values to plot, you should probably preallocate the plotting variables. E.g.,

n = numel(x0 : h : xn-h);
xp = zeros(n,1);
yp = zeros(n,1);
fp = zeros(n,1);
xp(1) = x0;
yp(1) = y;
fp(1) = f(x0);
etc.