math.exp(complex)

[David Eppstein]

Why doesn't this work?

import math
math.exp(1j*math.pi) Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: can't convert complex to float; use e.g. abs(z)

The expected answer, of course, is -1.

It does work if you do it like this:
math.e**(1j*math.pi)

(-1+1.2246467991473532e-16j)

So why not math.exp(complex)?

--
David Eppstein http://www.ics.uci.edu/~eppstein/
Univ. of California, Irvine, School of Information & Computer Science

[Raymond Hettinger]

[David Eppstein]

Why doesn't this work?

import math
math.exp(1j*math.pi) Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: can't convert complex to float; use e.g. abs(z)

The expected answer, of course, is -1.

It does work if you do it like this:
math.e**(1j*math.pi) (-1+1.2246467991473532e-16j)

So why not math.exp(complex)?

Use the cmath module for complex ops:

import cmath
import math
cmath.exp(1j*math.pi)

(-1+1.2246063538223773e-016j)
Raymond Hettinger

[John J. Lee]

David Eppstein <ep******@ics.uci.edu> writes:

Why doesn't this work?

import math
math.exp(1j*math.pi)

Traceback (most recent call last):

[...] So why not math.exp(complex)?

import cmath as math

:-)
John

[David Eppstein]

In article <EN*****************@nwrdny02.gnilink.net>,
"Raymond Hettinger" <vz******@verizon.net> wrote:

So why not math.exp(complex)?

Use the cmath module for complex ops:

Thanks, but then my next question is, why are math and cmath different
from each other?

And, is there any important difference (e.g. in numerical accuracy)
between cmath.exp(x) and math.e**x ?

--
David Eppstein http://www.ics.uci.edu/~eppstein/
Univ. of California, Irvine, School of Information & Computer Science