Is this true? $Reint{f(z)dz}=int{Re(f(z))dz}$ [closed]












1














I have to say if this is true or not and why.



Let f a complex function, then $$Reint_{gamma}{f(z)dz}=int_{gamma}{Re(f(z))dz}$$










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closed as off-topic by T. Bongers, Henrik, Kavi Rama Murthy, Cesareo, Chinnapparaj R Dec 8 at 4:56


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – T. Bongers, Henrik, Kavi Rama Murthy, Cesareo, Chinnapparaj R

If this question can be reworded to fit the rules in the help center, please edit the question.









  • 2




    No. ${}{}{}{}{}$
    – T. Bongers
    Dec 7 at 22:17






  • 2




    How about $dz$? Try integrating along an arc of the unit cicle $z=e^{i theta}$.
    – mlerma54
    Dec 7 at 22:32










  • Consider that the imaginary part of $f(z)$ could integrate to a real value, or vice versa. It depends a lot on the path $gamma$.
    – zahbaz
    Dec 7 at 23:13
















1














I have to say if this is true or not and why.



Let f a complex function, then $$Reint_{gamma}{f(z)dz}=int_{gamma}{Re(f(z))dz}$$










share|cite|improve this question















closed as off-topic by T. Bongers, Henrik, Kavi Rama Murthy, Cesareo, Chinnapparaj R Dec 8 at 4:56


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – T. Bongers, Henrik, Kavi Rama Murthy, Cesareo, Chinnapparaj R

If this question can be reworded to fit the rules in the help center, please edit the question.









  • 2




    No. ${}{}{}{}{}$
    – T. Bongers
    Dec 7 at 22:17






  • 2




    How about $dz$? Try integrating along an arc of the unit cicle $z=e^{i theta}$.
    – mlerma54
    Dec 7 at 22:32










  • Consider that the imaginary part of $f(z)$ could integrate to a real value, or vice versa. It depends a lot on the path $gamma$.
    – zahbaz
    Dec 7 at 23:13














1












1








1


0





I have to say if this is true or not and why.



Let f a complex function, then $$Reint_{gamma}{f(z)dz}=int_{gamma}{Re(f(z))dz}$$










share|cite|improve this question















I have to say if this is true or not and why.



Let f a complex function, then $$Reint_{gamma}{f(z)dz}=int_{gamma}{Re(f(z))dz}$$







integration complex-analysis






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share|cite|improve this question













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edited Dec 7 at 23:07









Jean-Claude Arbaut

14.7k63464




14.7k63464










asked Dec 7 at 22:13









Juan De Dios Rojas

222




222




closed as off-topic by T. Bongers, Henrik, Kavi Rama Murthy, Cesareo, Chinnapparaj R Dec 8 at 4:56


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – T. Bongers, Henrik, Kavi Rama Murthy, Cesareo, Chinnapparaj R

If this question can be reworded to fit the rules in the help center, please edit the question.




closed as off-topic by T. Bongers, Henrik, Kavi Rama Murthy, Cesareo, Chinnapparaj R Dec 8 at 4:56


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – T. Bongers, Henrik, Kavi Rama Murthy, Cesareo, Chinnapparaj R

If this question can be reworded to fit the rules in the help center, please edit the question.








  • 2




    No. ${}{}{}{}{}$
    – T. Bongers
    Dec 7 at 22:17






  • 2




    How about $dz$? Try integrating along an arc of the unit cicle $z=e^{i theta}$.
    – mlerma54
    Dec 7 at 22:32










  • Consider that the imaginary part of $f(z)$ could integrate to a real value, or vice versa. It depends a lot on the path $gamma$.
    – zahbaz
    Dec 7 at 23:13














  • 2




    No. ${}{}{}{}{}$
    – T. Bongers
    Dec 7 at 22:17






  • 2




    How about $dz$? Try integrating along an arc of the unit cicle $z=e^{i theta}$.
    – mlerma54
    Dec 7 at 22:32










  • Consider that the imaginary part of $f(z)$ could integrate to a real value, or vice versa. It depends a lot on the path $gamma$.
    – zahbaz
    Dec 7 at 23:13








2




2




No. ${}{}{}{}{}$
– T. Bongers
Dec 7 at 22:17




No. ${}{}{}{}{}$
– T. Bongers
Dec 7 at 22:17




2




2




How about $dz$? Try integrating along an arc of the unit cicle $z=e^{i theta}$.
– mlerma54
Dec 7 at 22:32




How about $dz$? Try integrating along an arc of the unit cicle $z=e^{i theta}$.
– mlerma54
Dec 7 at 22:32












Consider that the imaginary part of $f(z)$ could integrate to a real value, or vice versa. It depends a lot on the path $gamma$.
– zahbaz
Dec 7 at 23:13




Consider that the imaginary part of $f(z)$ could integrate to a real value, or vice versa. It depends a lot on the path $gamma$.
– zahbaz
Dec 7 at 23:13










2 Answers
2






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oldest

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3














$$Reint_{gamma}{frac{i}{z}text{ } dz}=-2pi$$



$$int_{0}^{2pi}-Refrac{1}{e^{it} }dt=int_{0}^{2pi}-costdt=0$$






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    1














    $dz$ is complex for a general path $gamma$. Your statement would be true if $gamma$ was on the real line. The point is that for two complex numbers $a$ and $b$, $Re(ab) neq Re(a)b$. Indeed, they are equal iff $b$ is real.






    share|cite|improve this answer




























      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      3














      $$Reint_{gamma}{frac{i}{z}text{ } dz}=-2pi$$



      $$int_{0}^{2pi}-Refrac{1}{e^{it} }dt=int_{0}^{2pi}-costdt=0$$






      share|cite|improve this answer


























        3














        $$Reint_{gamma}{frac{i}{z}text{ } dz}=-2pi$$



        $$int_{0}^{2pi}-Refrac{1}{e^{it} }dt=int_{0}^{2pi}-costdt=0$$






        share|cite|improve this answer
























          3












          3








          3






          $$Reint_{gamma}{frac{i}{z}text{ } dz}=-2pi$$



          $$int_{0}^{2pi}-Refrac{1}{e^{it} }dt=int_{0}^{2pi}-costdt=0$$






          share|cite|improve this answer












          $$Reint_{gamma}{frac{i}{z}text{ } dz}=-2pi$$



          $$int_{0}^{2pi}-Refrac{1}{e^{it} }dt=int_{0}^{2pi}-costdt=0$$







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Dec 7 at 23:01









          ryszard eggink

          308110




          308110























              1














              $dz$ is complex for a general path $gamma$. Your statement would be true if $gamma$ was on the real line. The point is that for two complex numbers $a$ and $b$, $Re(ab) neq Re(a)b$. Indeed, they are equal iff $b$ is real.






              share|cite|improve this answer


























                1














                $dz$ is complex for a general path $gamma$. Your statement would be true if $gamma$ was on the real line. The point is that for two complex numbers $a$ and $b$, $Re(ab) neq Re(a)b$. Indeed, they are equal iff $b$ is real.






                share|cite|improve this answer
























                  1












                  1








                  1






                  $dz$ is complex for a general path $gamma$. Your statement would be true if $gamma$ was on the real line. The point is that for two complex numbers $a$ and $b$, $Re(ab) neq Re(a)b$. Indeed, they are equal iff $b$ is real.






                  share|cite|improve this answer












                  $dz$ is complex for a general path $gamma$. Your statement would be true if $gamma$ was on the real line. The point is that for two complex numbers $a$ and $b$, $Re(ab) neq Re(a)b$. Indeed, they are equal iff $b$ is real.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Dec 8 at 0:22









                  maridia

                  1,06012




                  1,06012















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