File size: 8,402 Bytes
b1b3bae |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 |
Namespace MathEx.ODESolver
Public Class bulirschstoer
Public fc As fdelegate
Delegate Sub fdelegate(ByVal y As Double(), ByRef dy As Double())
Sub New()
End Sub
Sub DefineFuncDelegate(ByVal func As fdelegate)
Me.fc = func
End Sub
Sub f(ByVal y As Double(), ByRef dy As Double())
fc.Invoke(y, dy)
End Sub
Public Sub solvesystembulirschstoer(ByVal x1 As Double, ByVal x2 As Double, ByRef y As Double(), ByVal n As Integer, ByVal h As Double, ByVal err As Double, ByVal isabserr As Boolean)
Dim ya As Double() = New Double() {}
Dim yl As Double() = New Double() {}
Dim ym As Double() = New Double() {}
Dim dy As Double() = New Double() {}
Dim dz As Double() = New Double() {}
Dim s As Double() = New Double() {}
Dim dt(,) As Double
Dim d As Double()
Dim yg(,) As Double
Dim yh(,) As Double
Dim konv As Boolean = False
Dim bo As Boolean = False
Dim bh As Boolean = False
Dim fin As Boolean = False
Dim i As Integer = 0
Dim j As Integer = 0
Dim k As Integer = 0
Dim kk As Integer = 0
Dim l As Integer = 0
Dim m As Integer = 0
Dim jj As Integer = 0
Dim r As Integer = 0
Dim sr As Integer = 0
Dim ta As Double = 0
Dim xxfin As Double = 0
Dim a As Double = 0
Dim b As Double = 0
Dim c As Double = 0
Dim b1 As Double = 0
Dim fc As Double = 0
Dim g As Double = 0
Dim ho As Double = 0
Dim u As Double = 0
Dim v As Double = 0
Dim cycleflag As Integer = 0
ya = New Double((n + 1)) {}
yl = New Double((n + 1)) {}
ym = New Double((n + 1)) {}
dy = New Double((n + 1)) {}
dz = New Double((n + 1)) {}
s = New Double((n + 1)) {}
dt = New Double((n + 1), 8) {}
d = New Double(8) {}
yg = New Double(11, (n + 1)) {}
yh = New Double(111, (n + 1)) {}
xxfin = x2
cycleflag = -1
Do While True
If ((cycleflag = -1) Or (cycleflag = 22)) Then
Me.f(y, (dz))
bh = False
fin = False
i = 1
Do While (i <= n)
s(i) = 0
ya(i) = y(i)
k = 1
Do While (k <= 7)
dt(i, k) = 0
k += 1
Loop
i += 1
Loop
ho = h
If ((x1 + h) >= xxfin) Then
ho = (x2 - x1)
fin = True
End If
End If
If (((cycleflag = -1) Or (cycleflag = 20)) Or (cycleflag = 22)) Then
a = (ho + x1)
If (a = x1) Then
a = a
Return
End If
fc = 1.5
bo = False
m = 1
r = 2
sr = 3
jj = 0
End If
cycleflag = -1
j = 1
Do While (j <= 10)
If bo Then
d(2) = 1.7777777777778
d(4) = 7.1111111111111
d(6) = 28.444444444444
Else
d(2) = 2.25
d(4) = 9
d(6) = 36
End If
konv = False
If (j > 3) Then
konv = True
End If
If (j > 7) Then
l = 7
d(7) = 64
fc = (0.6 * fc)
Else
l = j
d(l) = (m * m)
End If
m = (m * 2)
g = (ho / Convert.ToDouble(m))
b = (g * 2)
If (bh And (j < 9)) Then
i = 1
Do While (i <= n)
ym(i) = yh(j, i)
yl(i) = yg(j, i)
i += 1
Loop
Else
kk = ((m - 2) / 2)
m -= 1
i = 1
Do While (i <= n)
yl(i) = ya(i)
ym(i) = (ya(i) + (g * dz(i)))
i += 1
Loop
k = 1
Do While (k <= m)
Me.f(ym, (dy))
i = 1
Do While (i <= n)
u = (yl(i) + (b * dy(i)))
yl(i) = ym(i)
ym(i) = u
u = Math.Abs(u)
If (u > s(i)) Then
s(i) = u
End If
i += 1
Loop
If ((k = kk) And (k <> 2)) Then
jj = (1 + jj)
i = 1
Do While (i <= n)
yh(jj, i) = ym(i)
yg(jj, i) = yl(i)
i += 1
Loop
End If
k += 1
Loop
End If
Me.f(ym, (dy))
i = 1
Do While (i <= n)
v = dt(i, 1)
dt(i, 1) = (((ym(i) + yl(i)) + (g * dy(i))) * 0.5)
c = dt(i, 1)
ta = c
If (l >= 2) Then
k = 2
Do While (k <= l)
b1 = (d(k) * v)
b = (b1 - c)
u = v
If (b <> 0) Then
b = ((c - v) / b)
u = (c * b)
c = (b1 * b)
End If
v = dt(i, k)
dt(i, k) = u
ta = (u + ta)
k += 1
Loop
End If
If (Not isabserr And (Math.Abs(Convert.ToDouble((y(i) - ta))) > (err * s(i)))) Then
konv = False
End If
If (isabserr And (Math.Abs(Convert.ToDouble((y(i) - ta))) > err)) Then
konv = False
End If
y(i) = ta
i += 1
Loop
If konv Then
x1 = a
h = (fc * h)
If fin Then
Return
End If
cycleflag = 22
Exit Do
End If
d(3) = 4
d(5) = 16
bo = Not bo
m = r
r = sr
sr = (m * 2)
j += 1
Loop
If (cycleflag = -1) Then
bh = Not bh
ho = (ho * 0.5)
h = ho
fin = False
cycleflag = 20
End If
Loop
End Sub
End Class
End Namespace |