function bvalue
%BVALUE: MATLAB script M-file that uses bvp4c 
%to find the air resistance coefficient b
%for a ballistic object modeled by physical
%(quadratic) air resistance.
%Author: Peter Howard
b0=0; %b0 is an initial guess at the air resistance
fzero(@height,b0)
%
function val=height(b)
%NONHEIGHT: Solves ODE for nonlinear air resistance
g = 9.81;
rhs = @(t,y) [y(2);-g+b*y(2)^2]; 
tspan = [0 .95];
y0 = [4.06 0];
[t,y]=ode45(rhs, tspan, y0);
val = y(end,1);