fdjac.bas

NEWT rutine from Numerical Recipes in C translated to VB6

Attribute VB_Name = "Module2"
Option Explicit

Const eps = 0.0001

Public Sub fdjac(ByVal n As Integer, ByRef x() As Double, ByRef fvec As Double, ByRef df() As Double)

Dim i As Integer, j As Integer, h As Double, temp As Double, f() As Double

ReDim f(1 To n)
For j = 1 To n
    temp = x(j)
    h = eps * Abs(temp)
    If h = 0# Then
        h = eps
    End If
    x(j) = temp + h
    h = x(j) - temp
    vecfunc n, x, f
    x(j) = temp
    For i = 1 To n
        df(i, j) = (f(j) - fvec(i)) / h
    Next i
Next j


End Sub