Code to input function

I want to make a code where user can input the the function and as the output they get plot of f(x) vs x and also the roots of that non linear equation.

Answer 1

[David Hill]

Plotting would not be a problem, but finding all the roots is a problem. Recommend looking at fzero

a=input('Function (example: @(x)x.*cos(x)-x.^2.*sin(x)+exp(-x)): ','s');
f=str2func(a);
x=-pi:.001:2*pi;
plot(x,f(x));

Answer 2

[Chunru]

% fstr = input("Key in a function of x (eg. x.^2 + 2*x - 1): ", "s")
fstr = "@(x) x.^2 + 2*x - 1";   % This is for on-line matlab
try
    % eval("f = "+ fstr )
    f = str2func(fstr)
    fplot(f)
    x1 = fzero(f, 0)
    title(fstr + ":  x1="+x1)
end

f = function_handle with value:
    @(x)x.^2+2*x-1

x1 = 0.4142

[Walter Roberson]

Do not use eval for this purpose, use str2func()