Error with MatLab Program

Question

I'm learning about programming in MATLAB and I'm getting some annoying problems with it

The error i get is the following:

"Error using feval
Argument must contain a string or function_handle.

Error in Trapecio (line 26)
 Area=(h/2)*(feval(a)+(2*s)+feval(b));"

I am putting sin(x) at the start of the program in this line:

f = input('introduce la funcion: ');

I am not sure what to do here. Any help would be appreciated!

clear all; 
clc; 

fprintf('Calculo de la integral por el metodo trapecial\n\n'); 

f=input('introduce la funcion: '); 

a=input('limite inferior: '); 

b=input('limite superior: '); 

n=input('numero de segmentos a dividir:'); 

x=a;

s=0;

h=(b-a)/n;

if n==1
    Area=(h/2)*(feval(a)+(2*s)+feval(b));
else
i=1;
for i=1:(n-1);
        x=x+h;
        s=s+subs(f,'x',x);
    %i=i+1;
end

Area=(h/2)*(feval(a)+(2*s)+feval(b));

disp('Area= ');

disp(Area);

end

Jaxor24 · Accepted Answer · 2014-05-17 03:34:38Z

1

Feval requires a function handle as the first argument. You are passing it a string. Use eval instead and pass it a string expression. Check the documentation for eval.

answered May 17, 2014 at 3:34

Jaxor24

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1 Comment

rayryeng Over a year ago

+1 on reading MATLAB documentation. Welcome to StackOverflow Jaxor24!

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