Bourbaki

Example 1

Tag 08CO, permanent. Cite it as [Bourbaki, Tag 08CO].

Functions of a Real Variable, chapter IV, § 2. LINEAR DIFFERENTIAL EQUATIONS

When EE is of finite dimension nn over R\mathbf{R} one can identify the endomorphism A(t)A(t) with its matrix (aij(t))\left(a_{ij}(t)\right) with respect to any basis of EE (Alg., II, p. 343); when one identifies a vector x∈Ex \in E with the column matrix (xj)(x_j) of its components with respect to the basis of EE under consideration the expression A(t).xA(t).x conforms to the general conventions of Algebra (Alg., II, p. 343, prop 2). In this case, equation (2) is equivalent to the system of scalar differential equations

dxidt=∑j=1naij(t)xj+bi(t)(1≤i≤n). \frac{dx_i}{dt} = \sum_{j=1}^n a_{ij}(t)x_j + b_i(t) \qquad (1 \leq i \leq n).

(3)

Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.

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Cites

Transcribed from the printed volume. Not translated.