code for a known answer

i have a code that plots a figure. Now say that i don't know what the value of 'a' is. I am trying to write a basic numerical code to find the value of 'a' from the figure/ info (not using really complexed matlab functions). I have a complexed matlab function that i am using to find 'a' also, (thanks Azzi). I plan to compare the basic numerical code with that found with the matlab function. Any help would be appreciated.

%Plots fourier transform.
  a=5;
  w=-a:a/100:a;
  F=2*sin(a*w)./w;
  plot(w,F)
%finds value of -a- using complexed matlab functions
x=get(gca,'xlim');
a1=x(end);
disp(a1);

Answer 1

[Azzi Abdelmalek]

x=get(gca,'xlim')
a=x(end)

[harley]

what does the gca bit mean? Gives me the correct right answer. Any ideas on a numerical approach without relying on complexed functions.

[Azzi Abdelmalek]

doc gca
doc gcf
doc gco