location of vector Taylor expansion remainder

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I know in 1-dimension case, $$f(x)=f(x_0)+f'(tildex_0)(x-x_0)$$ where $tildex_0$ lies between $x$ and $x_0$.



What about in k-dimension case? $$mathbff(mathbfx)=mathbff(mathbfx_0)+mathbff'(tildemathbfx_0)(mathbfx-mathbfx_0)$$
Does $mathbftildex_0$ still lies between $mathbfx$ and $mathbfx_0$?



If $mathbfxrightarrowmathbfx_0$, does $mathbftildex_0rightarrowmathbfx_0$?







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    The 1D case is a form of the mean value theorem. What do you expect for $k$ dimensions? What will happen to the derivative? What could "between" mean, as $x$ and $x_0$ are now points in $mathbbR^k$.
    – mvw
    Jul 25 at 22:12















up vote
0
down vote

favorite












I know in 1-dimension case, $$f(x)=f(x_0)+f'(tildex_0)(x-x_0)$$ where $tildex_0$ lies between $x$ and $x_0$.



What about in k-dimension case? $$mathbff(mathbfx)=mathbff(mathbfx_0)+mathbff'(tildemathbfx_0)(mathbfx-mathbfx_0)$$
Does $mathbftildex_0$ still lies between $mathbfx$ and $mathbfx_0$?



If $mathbfxrightarrowmathbfx_0$, does $mathbftildex_0rightarrowmathbfx_0$?







share|cite|improve this question

















  • 1




    The 1D case is a form of the mean value theorem. What do you expect for $k$ dimensions? What will happen to the derivative? What could "between" mean, as $x$ and $x_0$ are now points in $mathbbR^k$.
    – mvw
    Jul 25 at 22:12













up vote
0
down vote

favorite









up vote
0
down vote

favorite











I know in 1-dimension case, $$f(x)=f(x_0)+f'(tildex_0)(x-x_0)$$ where $tildex_0$ lies between $x$ and $x_0$.



What about in k-dimension case? $$mathbff(mathbfx)=mathbff(mathbfx_0)+mathbff'(tildemathbfx_0)(mathbfx-mathbfx_0)$$
Does $mathbftildex_0$ still lies between $mathbfx$ and $mathbfx_0$?



If $mathbfxrightarrowmathbfx_0$, does $mathbftildex_0rightarrowmathbfx_0$?







share|cite|improve this question













I know in 1-dimension case, $$f(x)=f(x_0)+f'(tildex_0)(x-x_0)$$ where $tildex_0$ lies between $x$ and $x_0$.



What about in k-dimension case? $$mathbff(mathbfx)=mathbff(mathbfx_0)+mathbff'(tildemathbfx_0)(mathbfx-mathbfx_0)$$
Does $mathbftildex_0$ still lies between $mathbfx$ and $mathbfx_0$?



If $mathbfxrightarrowmathbfx_0$, does $mathbftildex_0rightarrowmathbfx_0$?









share|cite|improve this question












share|cite|improve this question




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edited Jul 25 at 22:02









Bernard

110k635103




110k635103









asked Jul 25 at 22:01









Xingzhe He

63




63







  • 1




    The 1D case is a form of the mean value theorem. What do you expect for $k$ dimensions? What will happen to the derivative? What could "between" mean, as $x$ and $x_0$ are now points in $mathbbR^k$.
    – mvw
    Jul 25 at 22:12













  • 1




    The 1D case is a form of the mean value theorem. What do you expect for $k$ dimensions? What will happen to the derivative? What could "between" mean, as $x$ and $x_0$ are now points in $mathbbR^k$.
    – mvw
    Jul 25 at 22:12








1




1




The 1D case is a form of the mean value theorem. What do you expect for $k$ dimensions? What will happen to the derivative? What could "between" mean, as $x$ and $x_0$ are now points in $mathbbR^k$.
– mvw
Jul 25 at 22:12





The 1D case is a form of the mean value theorem. What do you expect for $k$ dimensions? What will happen to the derivative? What could "between" mean, as $x$ and $x_0$ are now points in $mathbbR^k$.
– mvw
Jul 25 at 22:12











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Consider $mathbb C$ which can be treated as $mathbb R^2$. Consider teh function $f(z)=e^z$. $e^0-e^2pi i=0$ cannot be written as $2pi i e^z$ for any $z$.






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    Consider $mathbb C$ which can be treated as $mathbb R^2$. Consider teh function $f(z)=e^z$. $e^0-e^2pi i=0$ cannot be written as $2pi i e^z$ for any $z$.






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      Consider $mathbb C$ which can be treated as $mathbb R^2$. Consider teh function $f(z)=e^z$. $e^0-e^2pi i=0$ cannot be written as $2pi i e^z$ for any $z$.






      share|cite|improve this answer























        up vote
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        up vote
        0
        down vote









        Consider $mathbb C$ which can be treated as $mathbb R^2$. Consider teh function $f(z)=e^z$. $e^0-e^2pi i=0$ cannot be written as $2pi i e^z$ for any $z$.






        share|cite|improve this answer













        Consider $mathbb C$ which can be treated as $mathbb R^2$. Consider teh function $f(z)=e^z$. $e^0-e^2pi i=0$ cannot be written as $2pi i e^z$ for any $z$.







        share|cite|improve this answer













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        answered Jul 25 at 23:31









        Kavi Rama Murthy

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