Recent content by StumpedPupil

  1. S

    Find a linear fractional transformation that carries circle to a line.

    I'm sorry, that is a typo. I meant to write Re((1 + i)w) = 0. This is the line y = x. I choose two points on this line, and a point at infinity.
  2. S

    Find a linear fractional transformation that carries circle to a line.

    Homework Statement Define L: |z| = 1 -----> Re( (1 + w)) = 0. Find L. Homework Equations A transformation is defined by three unique points by T(z) = (z-z1)(z2-z3) / (z-z3)(z2-z1). If we have two transformations T and S, and we want T = S for three distinct points, then we have the...
  3. S

    Definite Integral using Residue Thm

    Ok, yeah I foolishly wrote the answer is arcsine but it is actually π/4 * 1/sin(3π/8).
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    Definite Integral using Residue Thm

    Homework Statement Calculate the integral [ z^4/(1 + z^8) ] over negative infinity to positive infinity. Homework Equations Residue Theorem. Specifically for real-valued rational functions (on the real axis) where the denominator exceeds the degree of the numerator by at least two or...
  5. S

    Evaluate the integral using the residue theorem and its applications.

    Yes, only four poles are in the upper half plane, namely the values for the variable w, which I mistakenly labeled as a z when z already existed. So I will integrate over the semi circle for very large R in the upper half plane for the poles z = e^(πiw), where w =1/8, 3/8, 5/8 and 7/8. Thank...
  6. S

    Evaluate the integral using the residue theorem and its applications.

    Homework Statement the integral from negative infinity to positive infinity: z^4/(1 + z^8)dz Homework Equations The residue theorem: <http://en.wikipedia.org/wiki/Residue_theorem>. The Attempt at a Solution I found the 8th roots of z^8 = -1, which are e^(πiz), where z =1/8, 3/8...
  7. S

    Show Res(F'(z)/F(z), z0) = m if F(z) is analytic and has a zero of order m at z0.

    It definitely helps, thank you. I do have a follow up question though. In the general case where F has a zero of order m and we represent F = (z-z0)^mg(z), like you did, then we can get F'/F = m/(z-z0) + g'(z)/g(z). The only condition of g(z) is that it is analytic, so is it not possible...
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    Show Res(F'(z)/F(z), z0) = m if F(z) is analytic and has a zero of order m at z0.

    Homework Statement Show Res(F'(z)/F(z), z0) = m if F(z) is analytic on the disc |z - z0| < R and has a zero of order m at z0. Homework Equations The Attempt at a Solution We know that the kth derivation of F(z) is 0 for all k less than m, since F(z) has a zero of order m at z0...
  9. S

    Consequences of Cauchy's Formula (differential formula)

    Homework Statement How does Cauchy's Formula help find the power series of the complex function f(z) = e^z. Homework Equations e^z = ∑z^k/k! (sum from k = 0 to infinity) Cauchy's Formula Consequence of Cauchy's Formula: F(z) is analytic in a domain D and the point z1 is in D. If...
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    Application of Cauchy's formula for trigonometric integrals.

    That doesn't actually help because you end with the same results. The denominator becomes (3 - cos(2θ)), which you can derive ∫4iz/(z^4 - 6z^2 + 1)dz from. Thanks for the suggestion though.
  11. S

    Application of Cauchy's formula for trigonometric integrals.

    Homework Statement ∫dθ/(1 + (sinθ)^2 ), [0, π] Homework Equations Cauchy's Formula, perhaps Cauchy's Thm. http://mathworld.wolfram.com/CauchyIntegralFormula.html http://mathworld.wolfram.com/CauchyIntegralTheorem.html The Attempt at a Solution I first substituted sinθ =...
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