text: # 1^i = e^(-2pi)?
  
  #### devire
  
  Registered Member
  got another complex analysis question for u guys and girls here. would 1^i = e^(-2pi), since e^(2pi*i) = 1, making 1^i = e^(2pi*i*i) = e^(-2pi) = 1 / e^(2pi). i tried it with my TI-83 calculator and it just gave me 1. so, which is it?
  
  oh and "pi" = 3.14..., i don't know how to make the symbol so i just say "pi".
  
  edit: i know this is probably wrong, but since 1 = e^0 = e^(2pi*i), wouldn't that make 2pi*i == 0, making 0 * i == -2pi?
  
  Last edited:
  devire said:
  since e^(2pi*i) = 1
  I haven't studies math for forty years, but . . .
  doesn't e^(n.pi*i) = 1 where n is ANY even integer. So why pick on n = 2?
  No power of 1 can ever deviate from unity, can it?
  
  EEEk!
  
  The thing is, you can rewrite a power using exponents and logs:
  $$1^i = (e^{\log 1})^i = e^{i \log 1}$$
  However, as River Ape pointed out, $$\log 1$$ isn't well defined in complex numbers. $$2 \pi i k$$ works $$\forall k \in Z$$. So there are infinitely many answers:
  $$1^i = e^{i \log 1} = e^{i 2 \pi i k} = e^{-2 \pi k}$$
  
  http://en.wikipedia.org/wiki/Complex_logarithm#Log.28z.29_as_a_multi-valued_function
  
  You can turn log into a single valued function by putting an arbitrary branch cut somewhere (e.g. force the imaginary part to be $$\in (- \pi, \pi]$$ by convention) which is probably what your calculator did.
  
  TI calculators (the only ones I've ever used) always give values on the principle branch of the function.
  
  A similar problem arises when you try to compute arctangents. This is something the undergrads in my class never understand completely.
  
  I haven't studies math for forty years, but . . .
  doesn't e^(n.pi*i) = 1 where n is ANY even integer. So why pick on n = 2?
  No power of 1 can ever deviate from unity, can it?
  
  No, e^(n*pi*i) is 1 for n even, and -1 for n odd. Each increment of pi takes you half way around the unit circle.
  
  I haven't studies math for forty years, but . . .
  doesn't e^(n.pi*i) = 1 where n is ANY even integer. So why pick on n = 2?
  No power of 1 can ever deviate from unity, can it?
  
  for 1 and -1 raised to real powers, yes. but not when 1 or -1 is raised to a complex number, for example, (-1)^(-i) = e^pi.
  
  P.S. why did u stop studying math for so long? u probably studied math pretty well if u could remember that after 40 years.
  
  Last edited:
  I haven't studies math for forty years, but . . .
  doesn't e^(n.pi*i) = 1 where n is ANY even integer. So why pick on n = 2?
  No power of 1 can ever deviate from unity, can it?
  
  Just to pick on you a bit more, the roots of unity are a very important mathematical concept. An n[sup]th[/sup] root of unity is a complex number that satisfies $$z^n=1$$. Raising both sides to the 1/n power yields z=1[sup](1/n)[/sup], hence the name "root of unity". For more, see http://en.wikipedia.org/wiki/Root_of_unity and http://mathworld.wolfram.com/RootofUnity.html as starters.
  
  edit: i know this is probably wrong, but since 1 = e^0 = e^(2pi*i), wouldn't that make 2pi*i == 0, making 0 * i == -2pi?
  
  They way I see it, the only way 2pi*i can be o is when i = o :shrug:
explanation: The document is a discussion thread from a forum where a user named devire is asking a question about complex analysis, specifically about the value of \(1^i\). The user is questioning whether \(1^i = e^{-2\pi}\) and provides some reasoning based on the properties of complex exponentials. Other users respond with explanations and additional insights, including the concept of the complex logarithm and the multi-valued nature of the logarithm in the complex plane.
  
  The document contains a question and multiple answers.
distilabel_metadata.content: Evaluate the user given text extract and determine if it contains a math question and optionally and answer to this question.
  
  Output rules:
  
  1. Briefly describe the document and mention if it contains a question or a question and answer.
  2. Finalize the output with: Label: no-question,question,question-and-answer,multiple-question,multiple-question-and-answer
distilabel_metadata.role: system
distilabel_metadata.content: # 1^i = e^(-2pi)?
  
  #### devire
  
  Registered Member
  got another complex analysis question for u guys and girls here. would 1^i = e^(-2pi), since e^(2pi*i) = 1, making 1^i = e^(2pi*i*i) = e^(-2pi) = 1 / e^(2pi). i tried it with my TI-83 calculator and it just gave me 1. so, which is it?
  
  oh and "pi" = 3.14..., i don't know how to make the symbol so i just say "pi".
  
  edit: i know this is probably wrong, but since 1 = e^0 = e^(2pi*i), wouldn't that make 2pi*i == 0, making 0 * i == -2pi?
  
  Last edited:
  devire said:
  since e^(2pi*i) = 1
  I haven't studies math for forty years, but . . .
  doesn't e^(n.pi*i) = 1 where n is ANY even integer. So why pick on n = 2?
  No power of 1 can ever deviate from unity, can it?
  
  EEEk!
  
  The thing is, you can rewrite a power using exponents and logs:
  $$1^i = (e^{\log 1})^i = e^{i \log 1}$$
  However, as River Ape pointed out, $$\log 1$$ isn't well defined in complex numbers. $$2 \pi i k$$ works $$\forall k \in Z$$. So there are infinitely many answers:
  $$1^i = e^{i \log 1} = e^{i 2 \pi i k} = e^{-2 \pi k}$$
  
  http://en.wikipedia.org/wiki/Complex_logarithm#Log.28z.29_as_a_multi-valued_function
  
  You can turn log into a single valued function by putting an arbitrary branch cut somewhere (e.g. force the imaginary part to be $$\in (- \pi, \pi]$$ by convention) which is probably what your calculator did.
  
  TI calculators (the only ones I've ever used) always give values on the principle branch of the function.
  
  A similar problem arises when you try to compute arctangents. This is something the undergrads in my class never understand completely.
  
  I haven't studies math for forty years, but . . .
  doesn't e^(n.pi*i) = 1 where n is ANY even integer. So why pick on n = 2?
  No power of 1 can ever deviate from unity, can it?
  
  No, e^(n*pi*i) is 1 for n even, and -1 for n odd. Each increment of pi takes you half way around the unit circle.
  
  I haven't studies math for forty years, but . . .
  doesn't e^(n.pi*i) = 1 where n is ANY even integer. So why pick on n = 2?
  No power of 1 can ever deviate from unity, can it?
  
  for 1 and -1 raised to real powers, yes. but not when 1 or -1 is raised to a complex number, for example, (-1)^(-i) = e^pi.
  
  P.S. why did u stop studying math for so long? u probably studied math pretty well if u could remember that after 40 years.
  
  Last edited:
  I haven't studies math for forty years, but . . .
  doesn't e^(n.pi*i) = 1 where n is ANY even integer. So why pick on n = 2?
  No power of 1 can ever deviate from unity, can it?
  
  Just to pick on you a bit more, the roots of unity are a very important mathematical concept. An n[sup]th[/sup] root of unity is a complex number that satisfies $$z^n=1$$. Raising both sides to the 1/n power yields z=1[sup](1/n)[/sup], hence the name "root of unity". For more, see http://en.wikipedia.org/wiki/Root_of_unity and http://mathworld.wolfram.com/RootofUnity.html as starters.
  
  edit: i know this is probably wrong, but since 1 = e^0 = e^(2pi*i), wouldn't that make 2pi*i == 0, making 0 * i == -2pi?
  
  They way I see it, the only way 2pi*i can be o is when i = o :shrug:
distilabel_metadata.role: user
distilabel_metadata.raw_output_q_a_detector_0: The document is a discussion thread from a forum where a user named devire is asking a question about complex analysis, specifically about the value of \(1^i\). The user is questioning whether \(1^i = e^{-2\pi}\) and provides some reasoning based on the properties of complex exponentials. Other users respond with explanations and additional insights, including the concept of the complex logarithm and the multi-valued nature of the logarithm in the complex plane.
  
  The document contains a question and multiple answers.
  
  Label: question-and-answer