Scala sqrt类代码示例

//设置package包名称以及导入依赖的类
import scala.annotation.tailrec
import scala.collection.GenSeq
import scala.math.sqrt

package object PageRank {

  type LinkMat = GenSeq[(Int,Int)]

  def sumElements(R: GenSeq[Float], A: LinkMat, j: Int): Float = {
    // sums all PageRanks / number of links for a column j
    val totalLinks = A.filter(_._2==j)
    if (totalLinks.isEmpty) sys.error("No link in the page " + j + " at sumElements")
    else R(j)/totalLinks.size
  }

  // find all pages pointing to i A(i,j) exists
  def findConnected(i: Int, A: LinkMat):GenSeq[Int] = A.filter(_._1==i).map(_._2).toSeq

  def converged(r1: GenSeq[Float], r2: GenSeq[Float], eps: Float): Boolean = {
    val totSquare: Float = r1.zip(r2).map(p=>(p._1-p._2)*(p._1-p._2)).sum
    sqrt(totSquare/r1.size)<=eps
  }

  @tailrec def compRank(R: GenSeq[Float], A: LinkMat, damp: Float, eps: Float, niter: Int = 0,niterMax: Int = 10000): GenSeq[Float] = {
    val rankIndex: GenSeq[Int] = 0 until R.size
    val rightRank: GenSeq[Float] = rankIndex map{i:Int =>
      val connected = findConnected(i,A)
      connected.map{j:Int => sumElements(R, A, j)}.sum
    }
    val newRank = rightRank map {damp*_ + (1-damp)/R.size}
    if(converged(newRank,R,eps)) newRank
    else if(niter>=niterMax) {
      println("Max iteration reached")
      newRank
    } else compRank(newRank,A,damp,eps,niter+1,niterMax)
  }
} 

//设置package包名称以及导入依赖的类
package com.hugemane.sudoku.solver.service.partition

import com.hugemane.sudoku.solver.BoardPoint.Point
import com.hugemane.sudoku.solver.model.{ Block, SudokuBoard }

import scala.math.sqrt

trait BoardPatchPartitioner {

  def partitionIntoPatches(board: SudokuBoard): List[Map[Point, Block]] = {
    val rowSeparation = sqrt(board.rows)
    val columnSeparation = sqrt(board.columns)

    //todo: solve (get past for now to solve maximum amount of problems)
    val patch1 = board.blocks.filter(x => List((0, 0), (0, 1), (1, 0), (1, 1)).contains(x._1))
    val patch2 = board.blocks.filter(x => List((0, 2), (0, 3), (1, 2), (1, 3)).contains(x._1))
    val patch3 = board.blocks.filter(x => List((2, 0), (2, 1), (3, 0), (3, 1)).contains(x._1))
    val patch4 = board.blocks.filter(x => List((2, 2), (2, 3), (3, 2), (3, 3)).contains(x._1))

    List(patch1, patch2, patch3, patch4)
  }
} 

//设置package包名称以及导入依赖的类
package chapter.fourteen

import ExerciseTen.compose

import scala.math.sqrt

import org.scalatest._
import org.scalatest.junit.JUnitRunner
import org.junit.runner.RunWith

@RunWith(classOf[JUnitRunner])
class ExerciseTenSpec extends FlatSpec with Matchers {

  "compose" should "compose two functions, yielding another function of the same type" in {
    def f(x: Double) = if (x >= 0) Some(sqrt(x)) else None
    def g(x: Double) = if (x != 1) Some(1 / (x - 1)) else None
    val h = compose(f, g)

    h(2) should be ( Some(1.0) )
    h(1) should be ( None )
    h(0) should be ( None )
  }
} 

//设置package包名称以及导入依赖的类
package com.lljv.analytics.analyzerengine

import scala.math.pow
import scala.math.sqrt


object VectorUtils {

  def arrayNorm(array: Array[Double]): Double = {
    val arraySquared = array.map(pow(_, 2))
    val norm = sqrt(arraySquared.toSeq.sum)
    return norm
  }

  def arrayNorm(array: Array[Float]): Float = {
    val arrayDouble = array.map(_.toDouble)
    return arrayNorm(arrayDouble).toFloat
  }

  def normalizeVector(vector: Array[Double]): Array[Double] = {
    var normalizedVector: Array[Double] = vector
    val vectorNorm = arrayNorm(normalizedVector)
    if (vectorNorm > 1e-7) normalizedVector.map(_ / vectorNorm)
    return normalizedVector
  }

  def normalizeVector(array: Array[Float]): Array[Float] = {
    val arrayDouble: Array[Double] = array.map(_.toDouble)
    return normalizeVector(arrayDouble).map(_.toFloat)
  }

} 

//设置package包名称以及导入依赖的类
package lila.common

import scala.annotation._
import scala.math.{ pow, sqrt }
import scalaz.NonEmptyList

object Maths {

  def variance[T](a: NonEmptyList[T])(implicit n: Numeric[T]): Double = {
    val m = mean(a)
    a.map(i => pow(n.toDouble(i) - m, 2)).list.sum / a.size
  }

  def deviation[T](a: NonEmptyList[T])(implicit n: Numeric[T]): Double = sqrt(variance(a))

  // ridiculously performance optimized mean function
  def mean[T](a: NonEmptyList[T])(implicit n: Numeric[T]): Double = {
    @tailrec def recurse(a: List[T], sum: T, depth: Int): Double = {
      a match {
        case Nil => n.toDouble(sum) / depth
        case x :: xs => recurse(xs, n.plus(sum, x), depth + 1)
      }
    }
    recurse(a.tail, a.head, 1)
  }

  def median[T](a: NonEmptyList[T])(implicit n: Numeric[T]): Double = {
    val list = a.list
    val size = list.size
    val (lower, upper) = list.sorted.splitAt(size / 2)
    if (size % 2 == 0) (n.toDouble(lower.last) + n.toDouble(upper.head)) / 2.0
    else n toDouble upper.head
  }

  def truncateAt(n: Double, p: Int): Double = {
    val s = math.pow(10, p)
    (math floor n * s) / s
  }

  def toInt(l: Long): Int = l.min(Int.MaxValue).max(Int.MinValue).toInt
  def toInt(l: Option[Long]): Option[Int] = l map toInt
} 

//设置package包名称以及导入依赖的类
package org.singingwizard.util.collections

import scala.math.pow
import scala.math.sqrt

object MetricOperations {
  implicit class SetAddDiffVector[T](val underlying: collection.Set[T]) extends AnyVal {
    def differenceVector[N: Numeric](o: collection.Set[T], distance: N) = {
      (underlying ++ o).toSeq.map { e ?
        if (underlying(e) == o(e)) {
          implicitly[Numeric[N]].zero
        } else {
          distance
        }
      }
    }

    def differenceVector[N: Numeric](o: collection.Set[T], distance: (T) ? N) = {
      (underlying ++ o).toSeq.map { e ?
        if (underlying(e) == o(e)) {
          implicitly[Numeric[N]].zero
        } else {
          distance(e)
        }
      }
    }
  }

  implicit class DoubleSeqWithAdditional(val underlying: collection.Traversable[Double]) {
    def pNorm(p: Double) = {
      if (p == Double.PositiveInfinity || p == Double.NegativeInfinity) {
        underlying.max
      } else if (p == 1) {
        underlying.sum
      } else if (p == 2) {
        sqrt(underlying.map(x ? x * x).sum)
      } else {
        pow(underlying.map(pow(_, p)).sum, 1 / p)
      }
    }
  }

  implicit class IntSeqWithAdditional(val underlying: collection.Traversable[Int]) {
    def pNorm(p: Double): Double = {
      if (p == Double.PositiveInfinity || p == Double.NegativeInfinity) {
        underlying.max
      } else if (p == 1) {
        underlying.sum
      } else if (p == 2) {
        sqrt(underlying.map(x ? x * x).sum)
      } else {
        pow(underlying.map(pow(_, p)).sum, 1 / p)
      }
    }
  }
  
  implicit class BooleanWithAdditional(val underlying: Boolean) extends AnyVal {
    def ?>[N: Numeric](v: N) = if (underlying) v else implicitly[Numeric[N]].one
    def !?>[N: Numeric](v: N) = if (!underlying) v else implicitly[Numeric[N]].zero
  }
} 

//设置package包名称以及导入依赖的类
package com.cds.learnscala.chapter.chp14

import scala.None


  def swap[S, T](tup: (S, T)): (T, S) = {
    tup match {
      case (a, b) => (b, a)
    }
  }

  def swap1(array: Array[Any]) = {
    array match {
      case Array(first, second, [email protected]_*) => Array(second, first) ++ rest
      case _ => array
    }
  }

  def sum(lst: List[Option[Int]]) = {
    lst.map(_.getOrElse(0)).sum
  }

  def sum1(lst: List[Option[Int]]) = {
    var result = 0
    lst.foreach {
      case Some(a) => result += a
      case None => result
    }
    result
  }

  def compose(f: Double => Option[Double], g: Double => Option[Double]) = {
    (x: Double) =>
      if (f(x) == None || g(x) == None) None
      else g(x)
  }

  import scala.math.sqrt

  def f(x: Double) = if (x >= 0) Some(sqrt(x)) else None

  def g(x: Double) = if (x != 1) Some(1 / (x - 1)) else None


  def main(args: Array[String]) {

    println(swap[String, Int](("1", 2)))

    println(swap1(Array("1", "2", "3", "4")).mkString(","))

    val x = List(Some(1), None, Some(2), None, Some(3))
    println(sum(x))
    println(sum1(x))

    val h = compose(f, g)
    println(h(2))
  }

} 

//设置package包名称以及导入依赖的类
package skeleton

import display.fmt
import util.{Vec, TwoD}
import scala.math.{pow, abs, sqrt}

class Edge(val a: Corner, val b: Corner) {
  def asVec(): Vec = {
    return b-a
  }
  def distance(p: TwoD): Double =  {
    abs((b.y - a.y)*p.x - (b.x - a.x)*p.y + b.x*a.y - b.y*a.x) / sqrt(pow(b.y - a.y, 2) + pow(b.x - a.x, 2))
  }
  override def toString(): String = {
    "Edge(" + a + ", " + b + ")" 
  }
  override def equals(o: Any): Boolean = o match {
    case e: Edge => e.a == a && e.b == b
    case _ => false
  }
  override def hashCode = {
    (a.x + a.y + b.x + b.y).hashCode()
  }
}


object Edge {
  val debug = new Edge(new Corner(0,0), new Corner(1,0))
  def bisector(ep: Edge, en: Edge): Vec = {
    (-ep.asVec().unit + en.asVec().unit).unit
  }
} 

//设置package包名称以及导入依赖的类
package lila.common

import scala.annotation._
import scala.math.{ pow, sqrt }
import scalaz.{ NonEmptyList, IList, INil, ICons }

object Maths {

  def variance[T](a: NonEmptyList[T])(implicit n: Numeric[T]): Double = {
    val m = mean(a)
    a.map(i => pow(n.toDouble(i) - m, 2)).toList.sum / a.size
  }

  def deviation[T](a: NonEmptyList[T])(implicit n: Numeric[T]): Double = sqrt(variance(a))

  // ridiculously performance optimized mean function
  def mean[T](a: NonEmptyList[T])(implicit n: Numeric[T]): Double = {
    @tailrec def recurse(a: IList[T], sum: T, depth: Int): Double = {
      a match {
        case ICons(x, xs) => recurse(xs, n.plus(sum, x), depth + 1)
        case _ => n.toDouble(sum) / depth
      }
    }
    recurse(a.tail, a.head, 1)
  }

  def median[T](a: NonEmptyList[T])(implicit n: Numeric[T]): Double = {
    val list = a.toList
    val size = a.size
    val (lower, upper) = list.sorted.splitAt(size / 2)
    if (size % 2 == 0) (n.toDouble(lower.last) + n.toDouble(upper.head)) / 2.0
    else n toDouble upper.head
  }

  def truncateAt(n: Double, p: Int): Double = {
    val s = math.pow(10, p)
    (math floor n * s) / s
  }

  def toInt(l: Long): Int = l.min(Int.MaxValue).max(Int.MinValue).toInt
  def toInt(l: Option[Long]): Option[Int] = l map toInt
} 

//设置package包名称以及导入依赖的类
package pt1.week4

import breeze.linalg.{DenseMatrix, DenseVector}

import scala.math.{exp, sqrt}

object FuturesPricing {
  def calculateForShares(sharePriceLattice: DenseMatrix[Double], termInYears: Double, volatility: Double,
                         numberOfPeriods: Int, interestRate: Double, dividendYield: Double): Double = {
    val result = calculatePricingMatrix(sharePriceLattice, termInYears, volatility, numberOfPeriods, interestRate, dividendYield)

    result.apply(0, 0)
  }

  def calculate(priceLattice: DenseMatrix[Double], numberOfPeriods: Int, q: Double, p: Double): Double = {
    val result = calculatePricingMatrix(priceLattice, numberOfPeriods, q, p)

    result.apply(0, 0)
  }

  private[week4] def calculatePricingMatrix(sharePriceLattice: DenseMatrix[Double], termInYears: Double, volatility: Double, numberOfPeriods: Int, interestRate: Double, dividendYield: Double): DenseMatrix[Double] = {
    val u: Double = exp(volatility * sqrt(termInYears / numberOfPeriods))
    val d: Double = 1 / u
    val q: Double = (exp((interestRate - dividendYield) * termInYears / numberOfPeriods) - d) / (u - d)
    val p: Double = 1 - q
    calculatePricingMatrix(sharePriceLattice, numberOfPeriods, q, p)
  }

  private def calculatePricingMatrix(priceLattice: DenseMatrix[Double], numberOfPeriods: Int, q: Double, p: Double): DenseMatrix[Double] = {
    val n = numberOfPeriods + 1

    val result = DenseMatrix.zeros[Double](n, n)
    val lastColumnIndex = numberOfPeriods
    result(::, lastColumnIndex) := priceLattice(::, lastColumnIndex).slice(0, n)

    val columnsFromPriorToLastOneDownToFirst = (lastColumnIndex - 1) to 0 by -1
    for (i <- columnsFromPriorToLastOneDownToFirst) {
      val previousColumn = result(::, i + 1)
      val previousColumnShiftedOneDown = DenseVector.vertcat(previousColumn(1 until previousColumn.length), DenseVector.zeros[Double](1))
      val currentColumn = (previousColumnShiftedOneDown * q) + (previousColumn * p)
      result(::, i) += currentColumn
    }
    result
  }
} 

//设置package包名称以及导入依赖的类
package com.codiply.barrio.geometry

import scala.math.sqrt

import com.codiply.barrio.geometry.Point.Coordinates

final case class Metric(
    easyDistance: (Coordinates, Coordinates) => EasyDistance,
    easyDistanceToPlane: PartitioningPlane => Option[Coordinates => EasyDistance],
    toEasyDistance: RealDistance => Option[EasyDistance],
    toRealDistance: EasyDistance => Option[RealDistance])

final object Metric {
  import com.codiply.barrio.geometry.Point.Coordinates._

  val euclidean = Metric(
    easyDistance = (a: Coordinates, b: Coordinates) => EasyDistance(
      a.zip(b).map(t => {
        val diff = t._1 - t._2
        diff * diff
      }).sum),
    easyDistanceToPlane = (plane: PartitioningPlane) => {
      // This is a vector normal to the boundary
      val eta = subtract(plane.centroid1, plane.centroid2)
      val etaLengthSquared = innerProduct(eta, eta)
      if (etaLengthSquared == 0) {
        None
      } else {
        val midPoint = scale(0.5, add(plane.centroid1, plane.centroid2))
        Some((q: Coordinates) => {
          val qToMidpoint = subtract(midPoint, q)
          val product = innerProduct(qToMidpoint, eta)
          EasyDistance((product * product) / etaLengthSquared)
        })
      }
    },
    toEasyDistance = (realDistance: RealDistance) =>
      Some(EasyDistance(realDistance.value * realDistance.value)),
    toRealDistance = (easyDistance: EasyDistance) => {
      if (easyDistance.value < 0.0) {
        None
      } else {
        Some(RealDistance(sqrt(easyDistance.value)))
      }
    })
} 

//设置package包名称以及导入依赖的类
package calculator

object Polynomial {

  def computeDelta(a: Signal[Double], b: Signal[Double], c: Signal[Double]): Signal[Double] = {
    Signal {
      (b() * b()) - (4 * a() * c())
    }
  }

  def computeSolutions(a: Signal[Double], b: Signal[Double], c: Signal[Double], delta: Signal[Double])
  : Signal[Set[Double]] = {
    Signal {
      import scala.math.sqrt
      if (a() == 0 || delta() < 0)
        Set()
      else if (((-b() + sqrt(delta())) / (2 * a())) == ((-b() - sqrt(delta())) / (2 * a()))) {
        Set(((-b() + sqrt(delta())) / (2 * a())))
      } else {
        Set(((-b() + sqrt(delta())) / (2 * a())), ((-b() - sqrt(delta())) / (2 * a())))
      }
    }
  }

}