How to expand exponential of symbolic expression

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Saurabh Bhapkar
Saurabh Bhapkar 2013-11-4
回答： Sanil Mhatre 2016-12-8
Basically i have a huge expression that has a lot of exp((a+bi)*t) terms.
Where a and b are numeric.
What i want is to separate out exp(bi*t) so that i can expand it to cos(bt)+isin(bt). How do i do this?

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回答（3 个）

Sanil Mhatre
Sanil Mhatre 2016-12-8
Input
syms b t
rewrite(exp(bi*t),'sincos')
Output
cos(b*t) + sin(b*t)*1i end
Azzi Abdelmalek
Azzi Abdelmalek 2013-11-4
Why are you expecting exp(2*t)*exp(3i*t) ?
2*t and 3*i*t are the same degree
Try this
syms t
q=exp((*t+3i*t^2)
expand(q)
% Result
exp(2*t)*exp(t^2*3*i)
Walter Roberson
Walter Roberson 2013-11-4
exp(2*t)*exp(3i*t) expanded is exp(t)*exp(t)*exp(i*t)*exp(i*t)*exp(i*t) . Then automatically gather the identical terms to get exp(t)^2 * exp(i*t)^3 . There is no reason to expect that exp(2*t) * exp(3*i*t) would be given instead when you use expand()

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