Math.Sqrt(Double) 方法

定義

命名空間:

System

組件:

System.Runtime.dll

來源:

Math.cs

傳回指定數字的平方根。

public:
 static double Sqrt(double d);

public static double Sqrt (double d);

static member Sqrt : double -> double

Public Shared Function Sqrt (d As Double) As Double

參數

d

Double

要找出其平方根的數字。

傳回

Double

下表的其中一個值。

d 參數	傳回值
零或正數	d 的正平方根。
負	NaN
等於 NaN	NaN
等於 PositiveInfinity	PositiveInfinity

範例

正方形區域的平方根代表正方形的任何一邊的長度。 下列範例會顯示美國中某些城市的區域，並在每個城市的大小以方形表示時產生印象。

// Create an array containing the area of some squares.
Tuple<string, double>[] areas =
               { Tuple.Create("Sitka, Alaska", 2870.3),
                 Tuple.Create("New York City", 302.6),
                 Tuple.Create("Los Angeles", 468.7),
                 Tuple.Create("Detroit", 138.8),
                 Tuple.Create("Chicago", 227.1),
                 Tuple.Create("San Diego", 325.2) };

Console.WriteLine("{0,-18} {1,14:N1} {2,30}\n", "City", "Area (mi.)",
                  "Equivalent to a square with:");

foreach (var area in areas)
  Console.WriteLine("{0,-18} {1,14:N1} {2,14:N2} miles per side",
                    area.Item1, area.Item2, Math.Round(Math.Sqrt(area.Item2), 2));

// The example displays the following output:
//    City                   Area (mi.)   Equivalent to a square with:
//
//    Sitka, Alaska             2,870.3          53.58 miles per side
//    New York City               302.6          17.40 miles per side
//    Los Angeles                 468.7          21.65 miles per side
//    Detroit                     138.8          11.78 miles per side
//    Chicago                     227.1          15.07 miles per side
//    San Diego                   325.2          18.03 miles per side

open System

// Create a list containing the area of some cities.
let areas =
    [ "Sitka, Alaska", 2870.3
      "New York City", 302.6
      "Los Angeles", 468.7
      "Detroit", 138.8
      "Chicago", 227.1
      "San Diego", 325.2 ]

printfn "%-18s %14s} %2s\n" "City" "Area (mi.)" "Equivalent to a square with:"

for city, area in areas do
    printfn $"{city,-18} {area,14:N1} {Math.Round(Math.Sqrt(area), 2),14:N2} miles per side"

// The example displays the following output:
//    City                   Area (mi.)   Equivalent to a square with:
//
//    Sitka, Alaska             2,870.3          53.58 miles per side
//    New York City               302.6          17.40 miles per side
//    Los Angeles                 468.7          21.65 miles per side
//    Detroit                     138.8          11.78 miles per side
//    Chicago                     227.1          15.07 miles per side
//    San Diego                   325.2          18.03 miles per side

Module Example
   Public Sub Main()
      ' Create an array containing the area of some squares.
      Dim areas() As Tuple(Of String, Double) = 
                     { Tuple.Create("Sitka, Alaska", 2870.3), 
                       Tuple.Create("New York City", 302.6), 
                       Tuple.Create("Los Angeles", 468.7), 
                       Tuple.Create("Detroit", 138.8), 
                       Tuple.Create("Chicago", 227.1), 
                       Tuple.Create("San Diego", 325.2) }

      Console.WriteLine("{0,-18} {1,14:N1} {2,30}", "City", "Area (mi.)", 
                        "Equivalent to a square with:")
      Console.WriteLine()
      For Each area In areas
        Console.WriteLine("{0,-18} {1,14:N1} {2,14:N2} miles per side", 
                          area.Item1, area.Item2, Math.Round(Math.Sqrt(area.Item2), 2))        
      Next
   End Sub
End Module
' The example displays the following output:
'    City                   Area (mi.)   Equivalent to a square with:
'    
'    Sitka, Alaska             2,870.3          53.58 miles per side
'    New York City               302.6          17.40 miles per side
'    Los Angeles                 468.7          21.65 miles per side
'    Detroit                     138.8          11.78 miles per side
'    Chicago                     227.1          15.07 miles per side
'    San Diego                   325.2          18.03 miles per side

另請參閱

• Pow(Double, Double)