115 lines
3.6 KiB
VB.net
115 lines
3.6 KiB
VB.net
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#Region "Microsoft.VisualBasic::81dc3bbe4b63f750c4ac4b1effa1ee76, Microsoft.VisualBasic.Core\Extensions\Math\ScientificNotation.vb"
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' Author:
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'
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' asuka (amethyst.asuka@gcmodeller.org)
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' xie (genetics@smrucc.org)
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' xieguigang (xie.guigang@live.com)
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'
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' Copyright (c) 2018 GPL3 Licensed
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'
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'
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' GNU GENERAL PUBLIC LICENSE (GPL3)
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'
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'
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' This program is free software: you can redistribute it and/or modify
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' it under the terms of the GNU General Public License as published by
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' the Free Software Foundation, either version 3 of the License, or
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' (at your option) any later version.
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'
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' This program is distributed in the hope that it will be useful,
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' but WITHOUT ANY WARRANTY; without even the implied warranty of
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' MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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' GNU General Public License for more details.
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'
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' You should have received a copy of the GNU General Public License
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' along with this program. If not, see <http://www.gnu.org/licenses/>.
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' /********************************************************************************/
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' Summaries:
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' Module ScientificNotation
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'
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' Function: FormatScientificNotation, PowerLog10, UsingScientificNotation
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'
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'
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' /********************************************************************************/
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#End Region
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Imports System.Runtime.CompilerServices
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Imports System.Text.RegularExpressions
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Imports sys = System.Math
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Namespace Math
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''' <summary>
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''' 科学记数法
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''' </summary>
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Public Module ScientificNotation
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''' <summary>
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''' 返回零表示比较小的常数
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''' </summary>
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''' <param name="x"></param>
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''' <param name="INF">当位数超过这个值之后将会被判定为非常大或者非常小的一个数</param>
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''' <returns></returns>
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Public Function PowerLog10(x#, Optional INF% = 5) As Single
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Dim pow# = sys.Log10(sys.Abs(x))
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If pow < -INF Then
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Return pow
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End If
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If pow > INF Then
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Return pow
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End If
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Return 0
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End Function
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''' <summary>
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''' 是否需要科学记数法来格式化？
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''' </summary>
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''' <param name="x#"></param>
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''' <param name="INF%"></param>
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''' <returns></returns>
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Public Function UsingScientificNotation(x#, Optional INF% = 5) As Boolean
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Return ScientificNotation.PowerLog10(x, INF) <> 0!
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End Function
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''' <summary>
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''' 强制格式化为科学记数法
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''' </summary>
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''' <param name="decimal%"></param>
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''' <returns></returns>
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Public Function FormatScientificNotation(n#, decimal%) As String
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If n# = 0R Then
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Return "0"
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End If
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Dim power = Fix(sys.Log10(n))
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Dim s = n.ToString.Split("E"c, "e"c).First
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Dim t$() = s.Split("."c)
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' 处理整数部分
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Dim int As String = t(Scan0)
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Dim intpower = int.Length - 1
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If intpower > 0 Then ' 整数部分不止一个字符长度，即数位大于等于2
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int = int.First & "." & Mid(int, 1) & t(1)
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s = sys.Round(Val(int), [decimal])
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Else
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s = int & "." & t(1)
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s = sys.Round(Val(s), [decimal])
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End If
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s = s & $"E{power + intpower}"
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Return s
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End Function
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End Module
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End Namespace
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