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get normals TBD

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This commit is contained in:
Roland Grinis 2021-03-31 09:15:55 +01:00
parent 5abd63cde2
commit 706a44fd33
1 changed files with 8 additions and 4 deletions
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12
kmath-tensors/src/commonMain/kotlin/space/kscience/kmath/tensors/core/utils.kt
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@ -1,5 +1,7 @@
package space.kscience.kmath.tensors.core
import space.kscience.kmath.stat.RandomGenerator
import space.kscience.kmath.stat.samplers.BoxMullerNormalizedGaussianSampler
import space.kscience.kmath.structures.*
import kotlin.random.Random
import kotlin.math.*
@ -35,8 +37,10 @@ internal fun Buffer<Double>.array(): DoubleArray = when (this) {
is DoubleBuffer -> array
else -> throw RuntimeException("Failed to cast Buffer to DoubleArray")
}
internal inline fun getRandomNormals(n: Int, seed: Long): DoubleArray {
val u = Random(seed)
return (0 until n).map { sqrt(-2.0 * ln(u.nextDouble())) * cos(2.0 * PI * u.nextDouble()) }.toDoubleArray()
/*
internal inline fun getRandomNormals(n: Int,): DoubleArray {
val sampler = BoxMullerNormalizedGaussianSampler.of()
val chain = sampler.sample(RandomGenerator.default)
return (0 until n).map { chain.next() }.toDoubleArray()
}
*/