Derivative of a function with constants

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Georgios Markoulis 2022-1-13

编辑： Torsten 2022-1-14

Hello,

how can i calculate the derivative of a function like x*e^x(a*x^2+b*x+c), where a,b,c are constants(for example integers).

I tried syms x a b c and then

f=inline('ax^2+bx+c','x')

diff(f(x),x)

but then i get an error.

A function like that is easy enough without Matlab but i want the sum of y'''+y''-y'+y which needs a lot of calculation.

Thanks in advance.

jessupj 2022-1-13

编辑：jessupj 2022-1-13

maybe

a*x^2 + b*x +c

with multiplication operations? (always report details of the error... its easier to tell what the problem is that way)

Torsten 2022-1-13

syms x a b c
f = x*e^x*(a*x^2+b*x+c);
df = diff(f,x)

Thank you so much, do you know how to calculate also y'' and y'''

Torsten 2022-1-14

编辑：Torsten 2022-1-14

d2f = diff(f,x,2)
d3f = diff(f,x,3)
...
dnf = diff(f,x,n)    % n-th derivative, n has to be set to a value before

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