How to calculate Sin function quicker and more precisely?
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Published on 2012-10-08T13:06:17Z
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2012/10/09
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c++
|algorithms
I want to calculate y(n)=32677Sin(45/1024•n), where y is an integer and n ranges from 0 to 2048. How can I make this process quicker and more precisely?
Now I want to show you a reference answer:
Since Sin(a+b)=Sin(a)Cos(b)+Cos(a)Sin(b)
And Cos(a+b)=Cos(a)Cos(b)-Sin(a)Cos(b).
So I can store Sin(45/1024•1) andCos(45/1024•1) ` only.Then use this formula:
Sin(45/1024•2)=Sin(45/1024•1+45/1024•1),
Cos(45/1024•2)=Cos(45/1024•1+45/1024•1),
....
`Sin(45/1024•n)=Sin(45/1024•(n-1)+45/1024•1) `,
`Cos(45/1024•n)=Cos(45/1024•(n-1)+45/1024•1) `,
This way maybe quicker without storing large array.
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