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)
(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)
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
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)
5/6
>> double(ans)