Variable Substitution of a Function

Hi everyone,

I have a simple question, but yet I can't figure it out. I want to substitute (point + alfa * d) values over x values.

If you evaluate (point + alpha * d), result is [1 - alpha, 2 - alpha]. But when it comes to the substitution, it becomes [alpha - 1, alpha - 2]. Why is that? How can I make this correct? Thanks in advance.

variable_count = 2;
syms x [1 variable_count]
syms alpha

func = 3 * x1^2 + 2 * x1 * x2 + 2 * x2^2 + 7;
d = [-1 -1];
point = [1 2];

func_one = subs(func, x, point + alpha * d)

Answer 1

[Paul]

It is correct, isn't it?

x1^2 = (-x1)^2, x1*x2 = (-x1)*(-x2), and x2^2 = (-x2)^2

[Onur YURDAKUL]

Yes, silly me. I was expecting just a raw substitution but instead it also rearranges the function. Thanks for your answer.