What is this number called?












0














Sorry, pretty awful title to describe my question.



Sometimes I like playing around with series expansions for certain functions on Mathematica, and if the function has a singularity at a point $b$, sometimes the little suggestion box will say something like "Series around $ x=b$" and will give me a series expansion around that point. I know this number is special, I don't know why, but sometimes at that series expansion it will have the obvious singularity, like $dfrac{1}{x-b}$ and then after that a finite number followed by more powers of $x$ with coefficients.



What is that finite number called?










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  • What number?${}$
    – Git Gud
    Aug 11 '15 at 9:41










  • The coefficient of $(x-b)^0$? Is it the residue?
    – Empy2
    Aug 11 '15 at 9:45










  • I have an example: wolframalpha.com/input/?i=1%2F%28s*%28s%2B1%29%29 If you go to where it says Series expansion at s=0, it will give 1/s-1+s+.....i'm talking about the -1 in that series expansion. Its not always -1, and sometimes there is no constant term at a series expansion around a singularity, but is there a name for the constant term in a series expansion for a function around its singularity?
    – Dave huff
    Aug 11 '15 at 9:45










  • Don't you mean $(x-b)^{-1}$ ?
    – Yves Daoust
    Aug 11 '15 at 9:46










  • My bad on the description, its not a coefficient on any of the series terms, its a constant number, there is no x multiplying it.
    – Dave huff
    Aug 11 '15 at 9:47
















0














Sorry, pretty awful title to describe my question.



Sometimes I like playing around with series expansions for certain functions on Mathematica, and if the function has a singularity at a point $b$, sometimes the little suggestion box will say something like "Series around $ x=b$" and will give me a series expansion around that point. I know this number is special, I don't know why, but sometimes at that series expansion it will have the obvious singularity, like $dfrac{1}{x-b}$ and then after that a finite number followed by more powers of $x$ with coefficients.



What is that finite number called?










share|cite|improve this question
























  • What number?${}$
    – Git Gud
    Aug 11 '15 at 9:41










  • The coefficient of $(x-b)^0$? Is it the residue?
    – Empy2
    Aug 11 '15 at 9:45










  • I have an example: wolframalpha.com/input/?i=1%2F%28s*%28s%2B1%29%29 If you go to where it says Series expansion at s=0, it will give 1/s-1+s+.....i'm talking about the -1 in that series expansion. Its not always -1, and sometimes there is no constant term at a series expansion around a singularity, but is there a name for the constant term in a series expansion for a function around its singularity?
    – Dave huff
    Aug 11 '15 at 9:45










  • Don't you mean $(x-b)^{-1}$ ?
    – Yves Daoust
    Aug 11 '15 at 9:46










  • My bad on the description, its not a coefficient on any of the series terms, its a constant number, there is no x multiplying it.
    – Dave huff
    Aug 11 '15 at 9:47














0












0








0







Sorry, pretty awful title to describe my question.



Sometimes I like playing around with series expansions for certain functions on Mathematica, and if the function has a singularity at a point $b$, sometimes the little suggestion box will say something like "Series around $ x=b$" and will give me a series expansion around that point. I know this number is special, I don't know why, but sometimes at that series expansion it will have the obvious singularity, like $dfrac{1}{x-b}$ and then after that a finite number followed by more powers of $x$ with coefficients.



What is that finite number called?










share|cite|improve this question















Sorry, pretty awful title to describe my question.



Sometimes I like playing around with series expansions for certain functions on Mathematica, and if the function has a singularity at a point $b$, sometimes the little suggestion box will say something like "Series around $ x=b$" and will give me a series expansion around that point. I know this number is special, I don't know why, but sometimes at that series expansion it will have the obvious singularity, like $dfrac{1}{x-b}$ and then after that a finite number followed by more powers of $x$ with coefficients.



What is that finite number called?







calculus sequences-and-series terminology






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share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Aug 11 '15 at 9:50









joriki

170k10183343




170k10183343










asked Aug 11 '15 at 9:40









Dave huffDave huff

478211




478211












  • What number?${}$
    – Git Gud
    Aug 11 '15 at 9:41










  • The coefficient of $(x-b)^0$? Is it the residue?
    – Empy2
    Aug 11 '15 at 9:45










  • I have an example: wolframalpha.com/input/?i=1%2F%28s*%28s%2B1%29%29 If you go to where it says Series expansion at s=0, it will give 1/s-1+s+.....i'm talking about the -1 in that series expansion. Its not always -1, and sometimes there is no constant term at a series expansion around a singularity, but is there a name for the constant term in a series expansion for a function around its singularity?
    – Dave huff
    Aug 11 '15 at 9:45










  • Don't you mean $(x-b)^{-1}$ ?
    – Yves Daoust
    Aug 11 '15 at 9:46










  • My bad on the description, its not a coefficient on any of the series terms, its a constant number, there is no x multiplying it.
    – Dave huff
    Aug 11 '15 at 9:47


















  • What number?${}$
    – Git Gud
    Aug 11 '15 at 9:41










  • The coefficient of $(x-b)^0$? Is it the residue?
    – Empy2
    Aug 11 '15 at 9:45










  • I have an example: wolframalpha.com/input/?i=1%2F%28s*%28s%2B1%29%29 If you go to where it says Series expansion at s=0, it will give 1/s-1+s+.....i'm talking about the -1 in that series expansion. Its not always -1, and sometimes there is no constant term at a series expansion around a singularity, but is there a name for the constant term in a series expansion for a function around its singularity?
    – Dave huff
    Aug 11 '15 at 9:45










  • Don't you mean $(x-b)^{-1}$ ?
    – Yves Daoust
    Aug 11 '15 at 9:46










  • My bad on the description, its not a coefficient on any of the series terms, its a constant number, there is no x multiplying it.
    – Dave huff
    Aug 11 '15 at 9:47
















What number?${}$
– Git Gud
Aug 11 '15 at 9:41




What number?${}$
– Git Gud
Aug 11 '15 at 9:41












The coefficient of $(x-b)^0$? Is it the residue?
– Empy2
Aug 11 '15 at 9:45




The coefficient of $(x-b)^0$? Is it the residue?
– Empy2
Aug 11 '15 at 9:45












I have an example: wolframalpha.com/input/?i=1%2F%28s*%28s%2B1%29%29 If you go to where it says Series expansion at s=0, it will give 1/s-1+s+.....i'm talking about the -1 in that series expansion. Its not always -1, and sometimes there is no constant term at a series expansion around a singularity, but is there a name for the constant term in a series expansion for a function around its singularity?
– Dave huff
Aug 11 '15 at 9:45




I have an example: wolframalpha.com/input/?i=1%2F%28s*%28s%2B1%29%29 If you go to where it says Series expansion at s=0, it will give 1/s-1+s+.....i'm talking about the -1 in that series expansion. Its not always -1, and sometimes there is no constant term at a series expansion around a singularity, but is there a name for the constant term in a series expansion for a function around its singularity?
– Dave huff
Aug 11 '15 at 9:45












Don't you mean $(x-b)^{-1}$ ?
– Yves Daoust
Aug 11 '15 at 9:46




Don't you mean $(x-b)^{-1}$ ?
– Yves Daoust
Aug 11 '15 at 9:46












My bad on the description, its not a coefficient on any of the series terms, its a constant number, there is no x multiplying it.
– Dave huff
Aug 11 '15 at 9:47




My bad on the description, its not a coefficient on any of the series terms, its a constant number, there is no x multiplying it.
– Dave huff
Aug 11 '15 at 9:47










1 Answer
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This is usually called the constant term. See e.g. mathwords.






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    1 Answer
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    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    2














    This is usually called the constant term. See e.g. mathwords.






    share|cite|improve this answer


























      2














      This is usually called the constant term. See e.g. mathwords.






      share|cite|improve this answer
























        2












        2








        2






        This is usually called the constant term. See e.g. mathwords.






        share|cite|improve this answer












        This is usually called the constant term. See e.g. mathwords.







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        answered Aug 11 '15 at 9:50









        jorikijoriki

        170k10183343




        170k10183343






























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