Regarding continuous function not in the Disc algebra












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$begingroup$


Let $D={zinmathbb{C}: |z|<1}$.



$C(bar{D})={f:bar Dlongrightarrow mathbb{C}: f ;text{is continuous on}; bar{D}}$



$A(D)={fin C(bar{D}): f ;text{is analytic in} ;D}$
Can you give me example of a function which is in $C(bar{D})$ but not in $A(D)$? A function that is not analytic exactly at the boundary but continuous.










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$endgroup$








  • 1




    $begingroup$
    How about $zmapstooverline{z}$?
    $endgroup$
    – SmileyCraft
    Jan 10 at 16:03
















0












$begingroup$


Let $D={zinmathbb{C}: |z|<1}$.



$C(bar{D})={f:bar Dlongrightarrow mathbb{C}: f ;text{is continuous on}; bar{D}}$



$A(D)={fin C(bar{D}): f ;text{is analytic in} ;D}$
Can you give me example of a function which is in $C(bar{D})$ but not in $A(D)$? A function that is not analytic exactly at the boundary but continuous.










share|cite|improve this question









$endgroup$








  • 1




    $begingroup$
    How about $zmapstooverline{z}$?
    $endgroup$
    – SmileyCraft
    Jan 10 at 16:03














0












0








0





$begingroup$


Let $D={zinmathbb{C}: |z|<1}$.



$C(bar{D})={f:bar Dlongrightarrow mathbb{C}: f ;text{is continuous on}; bar{D}}$



$A(D)={fin C(bar{D}): f ;text{is analytic in} ;D}$
Can you give me example of a function which is in $C(bar{D})$ but not in $A(D)$? A function that is not analytic exactly at the boundary but continuous.










share|cite|improve this question









$endgroup$




Let $D={zinmathbb{C}: |z|<1}$.



$C(bar{D})={f:bar Dlongrightarrow mathbb{C}: f ;text{is continuous on}; bar{D}}$



$A(D)={fin C(bar{D}): f ;text{is analytic in} ;D}$
Can you give me example of a function which is in $C(bar{D})$ but not in $A(D)$? A function that is not analytic exactly at the boundary but continuous.







functional-analysis banach-algebras






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asked Jan 10 at 16:02









user31459user31459

284




284








  • 1




    $begingroup$
    How about $zmapstooverline{z}$?
    $endgroup$
    – SmileyCraft
    Jan 10 at 16:03














  • 1




    $begingroup$
    How about $zmapstooverline{z}$?
    $endgroup$
    – SmileyCraft
    Jan 10 at 16:03








1




1




$begingroup$
How about $zmapstooverline{z}$?
$endgroup$
– SmileyCraft
Jan 10 at 16:03




$begingroup$
How about $zmapstooverline{z}$?
$endgroup$
– SmileyCraft
Jan 10 at 16:03










1 Answer
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$begingroup$

Any function that is not differentiable will do. For instance $f(z)=|z|$.






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    0












    $begingroup$

    Any function that is not differentiable will do. For instance $f(z)=|z|$.






    share|cite|improve this answer









    $endgroup$


















      0












      $begingroup$

      Any function that is not differentiable will do. For instance $f(z)=|z|$.






      share|cite|improve this answer









      $endgroup$
















        0












        0








        0





        $begingroup$

        Any function that is not differentiable will do. For instance $f(z)=|z|$.






        share|cite|improve this answer









        $endgroup$



        Any function that is not differentiable will do. For instance $f(z)=|z|$.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 10 at 16:55









        Martin ArgeramiMartin Argerami

        126k1182181




        126k1182181






























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