Differential of a map $mathbb{T}^2 rightarrow S^2$











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I want to calculate the differential of a map from the 2-torus $mathbb{T}^2$ to the 2-sphere $S^2$. The map is given in the form $$f: (x,y) mapstobegin{pmatrix} x \ y \ Phi end{pmatrix} frac{1}{sqrt{x^2 + y^2 +Phi^2}},$$ defined in a neighbourhood $Sigma$ of a point, say around the point $(0,0)$. What is the procedure to calculate the differential at a point $xi in Sigma$, i.e. $df: T_ximathbb{T}^2 rightarrow T_{f(xi)}S^2?$ I guess for this one should switch to local coordinate charts (how does this look like in this concrete example?)?










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    I don't see how this defines a map on the torus, $x=0$ and $x=2pi$ should give the same image.
    – Christoph
    Nov 21 at 21:10










  • Sorry, I guess it is only defined in a neighbourhood of some point on the torus.
    – Breaking Mad
    Nov 21 at 22:01















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I want to calculate the differential of a map from the 2-torus $mathbb{T}^2$ to the 2-sphere $S^2$. The map is given in the form $$f: (x,y) mapstobegin{pmatrix} x \ y \ Phi end{pmatrix} frac{1}{sqrt{x^2 + y^2 +Phi^2}},$$ defined in a neighbourhood $Sigma$ of a point, say around the point $(0,0)$. What is the procedure to calculate the differential at a point $xi in Sigma$, i.e. $df: T_ximathbb{T}^2 rightarrow T_{f(xi)}S^2?$ I guess for this one should switch to local coordinate charts (how does this look like in this concrete example?)?










share|cite|improve this question




















  • 2




    I don't see how this defines a map on the torus, $x=0$ and $x=2pi$ should give the same image.
    – Christoph
    Nov 21 at 21:10










  • Sorry, I guess it is only defined in a neighbourhood of some point on the torus.
    – Breaking Mad
    Nov 21 at 22:01













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I want to calculate the differential of a map from the 2-torus $mathbb{T}^2$ to the 2-sphere $S^2$. The map is given in the form $$f: (x,y) mapstobegin{pmatrix} x \ y \ Phi end{pmatrix} frac{1}{sqrt{x^2 + y^2 +Phi^2}},$$ defined in a neighbourhood $Sigma$ of a point, say around the point $(0,0)$. What is the procedure to calculate the differential at a point $xi in Sigma$, i.e. $df: T_ximathbb{T}^2 rightarrow T_{f(xi)}S^2?$ I guess for this one should switch to local coordinate charts (how does this look like in this concrete example?)?










share|cite|improve this question















I want to calculate the differential of a map from the 2-torus $mathbb{T}^2$ to the 2-sphere $S^2$. The map is given in the form $$f: (x,y) mapstobegin{pmatrix} x \ y \ Phi end{pmatrix} frac{1}{sqrt{x^2 + y^2 +Phi^2}},$$ defined in a neighbourhood $Sigma$ of a point, say around the point $(0,0)$. What is the procedure to calculate the differential at a point $xi in Sigma$, i.e. $df: T_ximathbb{T}^2 rightarrow T_{f(xi)}S^2?$ I guess for this one should switch to local coordinate charts (how does this look like in this concrete example?)?







derivatives differential-geometry






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edited Nov 21 at 22:02

























asked Nov 21 at 20:58









Breaking Mad

581416




581416








  • 2




    I don't see how this defines a map on the torus, $x=0$ and $x=2pi$ should give the same image.
    – Christoph
    Nov 21 at 21:10










  • Sorry, I guess it is only defined in a neighbourhood of some point on the torus.
    – Breaking Mad
    Nov 21 at 22:01














  • 2




    I don't see how this defines a map on the torus, $x=0$ and $x=2pi$ should give the same image.
    – Christoph
    Nov 21 at 21:10










  • Sorry, I guess it is only defined in a neighbourhood of some point on the torus.
    – Breaking Mad
    Nov 21 at 22:01








2




2




I don't see how this defines a map on the torus, $x=0$ and $x=2pi$ should give the same image.
– Christoph
Nov 21 at 21:10




I don't see how this defines a map on the torus, $x=0$ and $x=2pi$ should give the same image.
– Christoph
Nov 21 at 21:10












Sorry, I guess it is only defined in a neighbourhood of some point on the torus.
– Breaking Mad
Nov 21 at 22:01




Sorry, I guess it is only defined in a neighbourhood of some point on the torus.
– Breaking Mad
Nov 21 at 22:01















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