Can someone explain the definition of primitive mapping

definitionintuitionreal-analysis

Definition: If $G$ maps an open set $E \subset R^n$ into $R^n$, and if there is an integer $m$ and a real function $g$ with domain $E$ such that $$G(x)=\sum_{i \neq m} x_i e_i +g(x) e_m,\, (x \in E)$$ then we call $G$ primitive.

Can someone explain this definition? How to understand primitive and related equation?

Best Answer

Since not all notions in the question are defined, we try to guess their meaning. We have that $R^n$ probably is $\Bbb R^n$, $e_i$ is the standard basis vector of $\Bbb R^n$ such that its $i$-th coordinate is $1$ and the other coordinates are zeroes, given $x\in E\subset \Bbb R^n$, $x=\sum_{i=1}^n x_ie_i$ is the decomposition of $x$ with respect to the basis $\{e_i\}$, that is $x_i$ is the $i$-th coordinate of $x$ for each $1\le i\le n$. Then $G$ is primitive means that $G$ is the identity map on $E$ distorted on $m$-th coordinate for some $1\le m\le n$ by some function $g:E\to\Bbb R$. In particular, if $g(x)=x_m$ for each $x\in E$ then $G$ is the identity map.