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trig identities in java

paulbok · 2014-12-22 23:23:30

I'm trying to use a formula that has sin^2(x/2) (sin squared x, not sin x squared) in it, but Math.sin^2 doesn't exist in the Math method. Does anyone know how to express it in java? I've found examples that give sin(x/2) or has sin(x/2)*sin(x/2) but they don't give the correct result. I've found one alternative, sin^2 =…

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23-12-2014 12:23am

#1

paulbok

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I'm trying to use a formula that has sin^2(x/2) (sin squared x, not sin x squared) in it, but Math.sin^2 doesn't exist in the Math method.

Does anyone know how to express it in java?

I've found examples that give sin(x/2) or has sin(x/2)*sin(x/2)
but they don't give the correct result.

I've found one alternative, sin^2 = 1/2 - 1/2cos(2x) but that doesn't work for me either.

it's the Haversine formula for working out distance along the earths surface from to lat/long points.

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#2 23-12-2014 12:50am
GreeBo

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Sin squared x is equal to sin x * sin x

It's written that way to about confusion with sin ( x*x)

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#3 23-12-2014 1:01am
paulbok

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Right so, back to the drawing board then.

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#4 23-12-2014 1:15am
GreeBo

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You could also Google and get several java implementations...

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