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Iosif Pinelis
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estimation of a vector-function

Let $x(t)\in C^1(\mathbb{R}_+,\mathbb{R}^m)$ be a vector-function such that

  1. $\|x(t)\|+\|\dot x(t)\|\to 0$ as $t\to\infty$ and
  2. for some real $c_1>0$ and all $t>0$ one has $\|x(t)\|\le c_1\|\dot x(t)\|$

Is it true that $\|x(t)\|\le c_2 e^{-c_3t}$ all $t>0$? Here $c_i$ are positive constants.