Matlab Solving Muller Method

Hi, I keep receiving an error and I can't figure out how to get around it.

function [v3]=ParachuteMuller(m0,m1,m2)

%2/11/2020 William D.

%MULLER'S METHOD: PROBLEM 7.11

ea=5;

es=1;

iter=1;

itermax=100;

g=9.81;

c=15;

v=35;

while es<ea && iter<itermax

f0=@(m0) (g*m0/c)*(1-e^(-c*t/m0))-v;

f1=@(m1) (g*m1/c)*(1-e^(-c*t/m1))-v;

f2=@(m2) (g*m2/c)*(1-e^(-c*t/m2))-v;

c=f2; %c value

h0=m1-m0; %h0 value

h1=m2-m1; %h1 value

delta0=(f1-f0)/(m1-m0); %delta0 calculated value

delta1=(f2-f1)/(m2-m1); %delta1 calculated value

a=(delta1-delta0)/(h1+h0); %calculated a value

b=a*h1+delta1; %calculated b value

if sign(b)==1 %for + value of b use +

m3=m2+(-2*c)/(b+sqrt(b^2-4*a*c));

elseif sign(b)==-1 %for - value b use -

m3=m2+(-2*c)/(b-sqrt(b^2-4*a*c));

end

if m3~=0

ea=abs((m3-m2)*100/m3); %calculated approx. error

end

m0=m1; %replace x0 with x1

m1=m2; %replace x1 with x2

m2=m3; %replace x2 with calculated x3 value

iter=iter+1; %increase iteration

end

%Nobody Cares, Work Harder

%Keep Hammering

end

ERROR MESSAGE:

Undefined operator '-' for input arguments of type 'function_handle'.

Error in ParachuteMuller (line 22)

delta0=(f1-f0)/(m1-m0); %delta0 calculated value

Answer 1

[Steven Lord]

f0=@(m0) (g*m0/c)*(1-e^(-c*t/m0))-v;

Nowhere have you defined e. If you wanted to compute the exponential, instead just call the exp function.

f0 = @(m0) (g*m0/c)*(1-exp(-c*t/m0))-v;

           f1=@(m1) (g*m1/c)*(1-e^(-c*t/m1))-v;
           f2=@(m2) (g*m2/c)*(1-e^(-c*t/m2))-v;
           c=f2;        %c value
           h0=m1-m0;    %h0 value
           h1=m2-m1;  %h1 value
           delta0=(f1-f0)/(m1-m0);  %delta0 calculated value

You cannot add or subtract function handles like you're trying to do on the line that defines delta0. You can add or subtract the values you get by evaluating function handles, however.

delta0 = (f1(2)-f0(1))./(m1-m0)

That example subtracts the value of f0 evaluated at m0 = 1 from the value of f1 evaluated at m1 = 2.