By Augustin Fruchard

The aim of those lecture notes is to strengthen a concept of asymptotic expansions for capabilities related to variables, whereas even as utilizing services regarding one variable and capabilities of the quotient of those variables. Such composite asymptotic expansions (CAsEs) are rather well-suited to describing options of singularly perturbed traditional differential equations close to turning issues. circumstances indicate internal and outer expansions close to turning issues. therefore our technique is heavily on the topic of the tactic of matched asymptotic expansions. situations provide designated benefits, even though. First, they supply uniform expansions close to a turning aspect and clear of it. moment, a Gevrey model of circumstances is out there and targeted within the lecture notes. 3 difficulties are awarded within which circumstances are worthwhile. the 1st program issues canard recommendations close to a a number of turning element. the second one program issues so-called non-smooth or angular canard recommendations. eventually an Ackerberg-O’Malley resonance challenge is solved.

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Extra info for Composite Asymptotic Expansions

Example text

X; Á/n has a CAsE 0ÄnÄN 1 (compatibility with product and sum). N / exists such that the remainder is bounded by L jÁjN . This is evident from the assumptions. 0/ D 0. x/ C g0 . xÁ / has a CAsE. u C v/. x/; g0 . xÁ / has a CAsE as Á tends to 0. x/; g0 . x/; 0/ C h 0; g0 . x/g0 . x/; g0 . x/; g0 . xÁ / by iterating this procedure. 0/ C g0 . 0/ as fast part. ˛1 ; ˇ1 ; r0 ; jÁj/ if has a Á 2 S2 ; jÁj < e Á0 . V /. x/ . x/. x/. f / Á 2 0 defined by . x/n . 10) 1 N . ÁN /. x/ Á . u 26 2 Composite Asymptotic Expansions: General Study Differentiation.

3). 1). 5. e ˛; e ˇ; 1:e // if 0 < e r 0 < r0 , 0 < ˛ < e ˛

5 Continuation of Composite Expansions Fig. 2 Some domains V and ˝ with different signs of , j j of V , thin line: that of ˝, their intersection in dark gray 35 and . 19. x/ C gn xÁ Án , as S2 3 Á ! ˛; ˇ; 1; /, ˛ D ˛1 ˇ2 and ˇ D ˇ1 ˛2 . Let > . ˛; ˇ; C ; / with > 0 arbitrarily small (Fig. 2). X; Á/ 7! X /Án as Á nD0 n tends to 0, uniformly on ˝. ˛1 ; ˇ1 ; r0 ; jÁj/ and has a CAsE there as Á ! 0. Remarks. 1. ˛; ˇ; 1; /. Signs of and are arbitrary. We will use this result particularly in the case < 0 < .