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Still, I have not seen anything like this in Taylor expansion. Perhaps the derivates were included in the coefficients but it doesn't say at which point it was evaluated and so on.blue_leaf77 said:I think the derivatives must have been absorbed into the definition of the coefficients, because in the end, the derivatives in Taylor expansion will be evaluated at the point around which the function is approximated.
Ah thank you, I've been searching for multi variable taylor expansion bit wasn't able to find one like your explanation. It really all makes sense now, thanksblue_leaf77 said:That's the Taylor expansion for three variables, up to the second order it goes like
$$
f(x_1,x_2,x_3) \approx f(a_1,a_2,a_3) + \sum_{i=1}^3 \frac{\partial f(a_1,a_2,a_3)}{\partial x_i} (x_i-a_i) + \frac{1}{2!}\sum_{i=1}^3\sum_{j=1}^3 \frac{\partial^2 f(a_1,a_2,a_3)}{\partial x_i \partial x_j} (x_i-a_i)(x_j-a_j)
$$
The first term of the expansion of ##\lambda## in that book is equal to the first term in the above formula, the next three terms linear in ##\pi##, ##s##. and ##p/n## belong to the second term (the one containing single summation), and the rest belong to the double summation term. It needs not specify around which point the function is approximated when it only wants to give a general expression.
A Taylor expansion with multi variables is a mathematical technique used to approximate a function with multiple variables using a series of polynomials. It is an extension of the Taylor series, which is used for approximating functions with a single variable.
A Taylor expansion with multi variables is useful because it allows us to approximate complex functions with multiple variables using a series of simple polynomials. This makes it easier to perform calculations and analyze the behavior of the function.
A Taylor expansion with multi variables is calculated by taking derivatives of the function with respect to each variable and evaluating them at a specific point. These derivatives are then used to construct a series of polynomials, which are added together to form the Taylor expansion.
The main difference between a Taylor expansion with multi variables and a Taylor series is that the former is used for functions with multiple variables, while the latter is used for functions with a single variable. Additionally, the Taylor expansion with multi variables involves taking partial derivatives, while the Taylor series only requires taking ordinary derivatives.
A Taylor expansion with multi variables has various applications in mathematics, physics, and engineering. It is commonly used in optimization problems, numerical analysis, and in the study of differential equations. It is also used in fields such as economics and statistics for modeling and prediction purposes.