如何解決MATLAB上的以下問題

Question

a(x) 這里是信號中使用的一種方程

Let
y(x) = x^3 + x^2 + x + 1
a(x) is inputed by the user so for example if user inputs
a(x) = D2 + D + 6
y(x)*a(x) = D2(x^3 + x^2 + x + 1) + D(x^3 + x^2 + x + 1) + 6(x^3 + x^2 + x + 1)
here D2(x^3 + x^2 + x + 1) = 6x + 2 and D(x^3 + x^2 + x + 1) = 3x^2 + 2x + 1
So D is differentiation and D2 is double differential

所以我想知道如何在 MATLAB 上做這樣的事情

Answer 1

使用 Matlab 符號計算工具箱https://www.mathworks.com/products/symbolic.html

Calculus
Evaluate exact analytical solutions for definite or indefinite integral, 
calculate derivatives of symbolic expressions or functions, 
and approximate functions using series expansions.