%task4
%
%Makes a plot of the relationship between velocity and hydraulic radius,
% all other variables constant. Allows you to choose a range of radius values that are
% for shallow and deep channels. To answer the question, All things being equal, is the velocity
% faster in a deeper or shallower channel?
%
%Author:  Wendy Bohon with significant help from David Raleigh, Feb. 26,
%2009.


function task4(width , shallowestDepth , deepestDepth , interval)

% vector of depths.  Put in the shallowest deoth, the spacing interval for
% plotting the data and then the deepest depth.  It works the best if you
% put in significantly different depths.
depths = [shallowestDepth:interval:deepestDepth];

%Hydralic Radius (R)= (w*d)/(w+2d) ; which is also A/P
hydraulicRadius = (width .* depths) ./ (width + 2 .* depths)

%This plots up a figure showing the relationship between velocity and
%hydraulic radius with all other variables being held steady.
figure (3)
plot(depths , hydraulicRadius , '*k--')
title('Relationship Between Velocity and Hydrulic Radius')
xlabel('Hydraulic Radius')
ylabel('Velocity')
print('radiusVelocity')