# Symbolic package

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The symbolic package is part of the octave-forge project.

Demo of Anonymous function to symbolic function and back to anonymous function and then the use of the interval pkg.

% this is just a formula to start with

% have fun and change it if you want to.

f=@(x) x.^2 +3*x-1 + 5*x.*sin(x);

% the next 2 line take the Anonymous function into a symbolic formula

syms x;

ff=formula(f(x));

% now calculate the derivative of the function

ffd=diff(ff);

% and convert it back to an Anonymous function

df=function_handle(ffd)

% this uses the interval pkg. to find all the roots between -15 an 10

fzero (f, infsup (-15, 10), df)

ans ⊂ 4×1 interval vector

[-5.743488743719015, -5.743488743719013] [-3.0962279604822407, -3.09622796048224] [-0.777688831121563, -0.7776888311215626] [0.22911205809043574, 0.2291120580904359]