[Numpy-discussion] Exponential function, sine function and cos function

2022-06-04 Thread Brinley Patterson
Hi,

By using the exponential equation:

exp(x) = (sum{k=0}{n} 1/ k! ) ^ x

the speed and accuracy of calculating exponent greatly increases. Plus it makes 
it easier to use with imaginary numbers. I have the python function code if you 
are interested to learn more about this. This equation can then be used to 
calculate sine and cos more efficiently using the exponent form of them both.

Kind regards,

Brinley
MSc Machine Learning
BSc Mathematical Physics
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[Numpy-discussion] Re: Exponential function, sine function and cos function

2022-06-04 Thread Andras Deak
On Fri, Jun 3, 2022, at 23:54, Brinley Patterson wrote:
> Hi,
>
> By using the exponential equation:
>
> exp(x) = (sum{k=0}{n} 1/ k! ) ^ x
>
> the speed and accuracy of calculating exponent greatly increases. Plus 
> it makes it easier to use with imaginary numbers. I have the python 
> function code if you are interested to learn more about this. This 
> equation can then be used to calculate sine and cos more efficiently 
> using the exponent form of them both.

Hi,

From the equation you posted it sounds like your recommendation is to compute 
`e` from a truncated Taylor series, and then raise that number to the `x`th 
power. But we already know "the" double-precision value of `e`, a.k.a. 
`exp(1)`. So the recommended alternative would be more work than using 
double-precision `e` and then raising _that_ to the `x`th power.

So this makes me think that I missed your point. Could you please try 
elaborating on your recommendation?

AndrĂ¡s

>
> Kind regards,
>
> Brinley
> MSc Machine Learning
> BSc Mathematical Physics
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