Help with coding (integral)

How can i solve this integral ((1/5*x)+1)*sqrt(1+exp(-2x)) by using Simpsons method? The upper limit is 1 and the lower limit is 0. I know how to solve it, but i keep getting these errors. It says "Invalid expression. Check for missin multiplication operator...".

[David Hill]

What have you done? Your equation should be:

eqn=@(x)((1/5*x)+1).*sqrt(1+exp(-2*x));

[leyla ahmed]

clear all 

a = 0; 
b = 1; 
n = 20; 
m = n/2; 

dx = (b-a)/n; 

x = a; 

sum_f = ((1/5*a)+1).*sqrt(1+exp(-2*a));
eqn = @(x) ((1/5*x)+1).*sqrt(1+exp(-2*x));
for i = 1:m-1
    x = x + dx; 
    sum_f = sum_f + 4*((1/5*x)+1).*sqrt(1+exp(-2*x));
    x = x + dx;
    sum_f = sum_ f + 2*((1/5*x)+1).*sqrt(1+exp(-2*x));
    end

x = x + dx; 
sum_f = sum_f + 4*((1/5*x)+1).*sqrt(1+exp(-2*x));
sum_f = sum_f + b/((1/5*b)+1).*sqrt(1+exp(-2*b));
  

[leyla ahmed]

This is what i got now, but i still get the same error.

Answer 1

[Stephan]

Typo in line 18 - use sum_f instead of sum_ f

a = 0; 
b = 1; 
n = 20; 
m = n/2; 

dx = (b-a)/n; 

x = a; 

sum_f = ((1/5*a)+1).*sqrt(1+exp(-2*a));
eqn = @(x) ((1/5*x)+1).*sqrt(1+exp(-2*x));
for i = 1:m-1
    x = x + dx; 
    sum_f = sum_f + 4*((1/5*x)+1).*sqrt(1+exp(-2*x));
    x = x + dx;
    sum_f = sum_f + 2*((1/5*x)+1).*sqrt(1+exp(-2*x));
    end

x = x + dx; 
sum_f = sum_f + 4*((1/5*x)+1).*sqrt(1+exp(-2*x));
sum_f = sum_f + b/((1/5*b)+1).*sqrt(1+exp(-2*b));

Answer 2

[David Hill]

a = 0; b = 1; n = 20; 
h = (b-a)/n; 
x = linspace(a,b,n+1); 
f = ((1/5*x)+1).*sqrt(1+exp(-2*x));
F = h/3*(f(1)+2*sum(f(2:2:end-1))+4*sum(f(1:2:end-1))+f(end));