Expanding a function:

The expand function will multiply out terms, and factor will do the opposite:

>> expand((x+2)*(x-1))

ans =

x^2 x-2

>> factor(ans)

ans =

(x 2)*(x-1)

The function subs will replace a value for the symbolic variable in an expression. For illustration,

>> myexp = x^3 + 3*x^2 - 2

myexp =

x^3 3*x^2-2

>> x = 3;

>> subs(myexp,x)

ans =

       52

With symbolic math, a MATLAB works by the default with rational numbers means that the outcomes are kept in fractional forms. For illustration, executing the addition 1/3 + 1/2 would generally answer in a double value:

>> 1/3 + 1/2

ans =

       0.8333

Though, by making the expression symbolic, the outcome is symbolic also. Any numeric function (example, double) could modify that:

>> sym(1/3 + 1/2)

ans =

5/6

>> double(ans)

ans =

       0.8333