??? Error using ==> inline.subsref at 14 Not enough inputs to inline function.

Hi everyone,

I'm trying to make a program that finds the roots of a function using the Secant method for a class project. In class we only use very simple Matlab commands so most of the stuff I found online was way over-complicated for me to understand and use.

So what's happening is I'm getting an error:

??? Error using ==> inline.subsref at 14

Not enough inputs to inline function.

Error in ==> secante at 9 z=b-((fx(b)*(b-a))/(fx(b)-fx(a)));

when running secante(0,2,0.000001) for the function (e^(-0.5*x))*(cos(3*x))-e^(-x)

If anyone can help me understand why this is happening and check if I'm making any other mistakes it would be deeply appreciated. Here's my code:

function R = secante(a,b,erro)

f=input('Inserir f(x)= ','s');

fx = inline(f);

e=(abs(b-a))/(abs(b));

n=3;

R(1)=a;

R(2)=b;

while (erro<e)

        z=b-((fx(b)*(b-a))/(fx(b)-fx(a)));
        a=b;
        b=z;
        e=((abs(b-a))/(abs(b)));
        R(n)=z;
        n=n+1;
end

Answer 1

[Walter Roberson]

MATLAB does not know the constant "e" and so thinks it is a variable. The user needs to enter

exp(-0.5*x)*cos(3*x)-exp(-x)

[Lionheart]

You're absolutely right! I was messing with my code for 3 hours and after all it was the fuction that was wrong. Thanks!