trigofunc.bas

vb实现最短路径Dijkstra算法

Attribute VB_Name = "trigofunc"
'  ==========================================
'  Dijkstra's algorithm to find Shortest Path
'  ==========================================
'
' E.W. Dijkstra is a Dutch professor in Computer
' Science, who did a lot of research in graphs.
'
' Dijkstra's algorithm is of use when working with
' directional graphs. It constructs the shortest path
' between a starting-node and a goal-node.
' It is assumed that every link between two nodes
' has a certain cost, and this algorithm finds the
' path between the two given nodes with the lowest cost.
'
' The idea of this VB project was to show the
' work of this algorithm in a visual way.
'
'    Screen-shot: dijkstra.gif
'
'
'    Visit my Homepage:
'    http://www.geocities.com/emu8086/vb/
'
'
'    Last Update: Saturday, July 20, 2002
'
'
'    Copyright 2002 Alexander Popov Emulation Soft.
'               All rights reserved.
'        http://www.geocities.com/emu8086/


Option Explicit

Public Const PI = 3.14159265359

Public Function Arcsin(X As Double) As Double
    If X = -1 Then
        Arcsin = -PI / 2
    ElseIf X = 1 Then
        Arcsin = PI / 2
    Else
        Arcsin = Atn(X / Sqr(-X * X + 1))
    End If
End Function

Public Function Arccos(X As Double) As Double
    If X = -1 Then
        Arccos = PI
    ElseIf X = 1 Then
        Arccos = 0
    Else
        Arccos = Atn(-X / Sqr(-X * X + 1)) + 2 * Atn(1)
    End If
End Function