% File: integralPlot.m Version 1
%
% A. O. Hausknecht Spring 2012
% Mathematics Department, UMass Dartmouth
%
%  integralPlot(Finline, x0, xMin, xMax, n, plotFtoo)
%
% PURPOSE: Automates the plotting of a function 
%   by an integeral, y(x)= integral(f(x), x0, x),
%   over an interval [xMin, xMax]  
%
% ITS PARAMETERS:
%   Finline: The f(x) represented as an inline function
%   x0: The integals lower limit
%   xMin, xMax: The ploting domain
%   n: The number of x-values sampled
%   plotFtoo: plots Finline as well when true or 1 is passed
%
function integralPlot(Finline, x0, xMin, xMax, n, plotFtoo)
%
% Generate n equally spaced x-values 
% bewteen xMin and xMax
x = linspace(xMin, xMax, n);
% Create an n y-values equal to zero
y = zeros([1,n ]);
% Evaluate the integral at the x-values
for i = 1:n
   % Use quadature to approximate the integral
   % of f(x) from xMin to x(i)
   y(i) = quad(Finline, x0, x(i));
   i++;
end
% Plot the integral of FLine
clf;
plot(x, y,'r', 'linewidth', 3);
yMin = min(y); yMax = max(y);
if (plotFtoo) 
% Add a plot of Finline
   yF = Finline(x);
   yFMin = min(yF); yFMax = max(yF); 
   yMin = min( [yMin yFMin]); yMax = max([yMax yFMax]);
   hold on;
   plot(x, yF, 'g', 'linewidth', 3);
   legend('y1(x) = integral(f(x), x)', 'y2(x) = f(x)');
   hold off;
end
% Set a a viewing rectangle 10% larger than the plot
yMin = yMin*1.1; yMax = yMax*1.1;
axis([xMin xMax yMin yMax]);
xlabel('x'); ylabel('y');
% Show the grid and draw axes
ax=gca();
set(ax, 'xgrid', 'on', 'ygrid', 'on');
line([xMin xMax],[0 0], 'linewidth', 4);
line([0 0],[yMin yMax], 'linewidth', 4);
end