N2fb N2fb_r N2gb N2gb_r N2pb N2pb_r

N2fb_r() Sub N2fb_r ( M As  Long, N As  Long, X() As  Double, B() As  Double, Info As  Long, YY() As  Double, IRev As  Long, Optional Iout As  Long = 0, Optional Info2 As  Long, Optional NFcall As  Long, Optional NFjcall As  Long, Optional Niter As  Long, Optional S As  Double, Optional NFGcal As  Long, Optional Rtol As  Double = -1, Optional Atol As  Double = -1, Optional MaxFcall As  Long = -1, Optional MaxIter As  Long = -1, Optional Dtype As  Long = -1, Optional Dfac As  Double = -1, Optional Dtol As  Double = -1, Optional D0 As  Double = -1, Optional Tuner1 As  Double = -1, Optional Xctol As  Double = -1, Optional Xftol As  Double = -1, Optional Lmax0 As  Double = -1, Optional Lmaxs As  Double = -1, Optional Sctol As  Double = -1, Optional Dltfdj As  Double = -1  ) Nonlinear least squares approximation (adaptive algorithm) (simply bounded) (Jacobian not required) (reverse communication version) Purpose This routine minimizes the sum of the squares of M nonlinear functions in N variables, subject to simple bound constraints B0(i) <= X(i) <= B1(i), 1 <= i <= N, by the adaptive algorithm which combines and augments a Gauss-Newton, Levenberg-Marquardt and other techniques for better convergence. minimize the sum of fi(x1, x2, ..., xn)^2 (sum for i = 1 to M) The user must provide the function values in accordance with IRev. Since the Jacobian is calculated by finite difference approximation within the routine, the user is not required to calculate the Jacobian. Parameters [in] M Number of data. (M > 0) [in] N Number of parameters. (0 < N <= M) [in,out] X() Array X(LX - 1) (LX >= N) [in] X must contain an initial estimate of the solution vector. [out] IRev = 0: Solution vector, i.e. best point so far found.   IRev = 1: The abscissa where the function value shoule be evaluated.   IRev = 3: Recent approximation of the solution vector. [in] B() Array B(LB1 - 1, LB2 - 1) (LB1 = 2, LB2 >= N) Lower and upper bounds on solution vector X.   B(0, I) <= X(I) <= B(1, I) (I = 0 to N-1) [out] Info = 0: Successful exit. (Sub-code is set to Info2) = -1: The argument M had an illegal value. (M < N) = -2: The argument N had an illegal value. (N < 1) = -3: The argument X() is invalid. = -4: The argument B() is invalid. = -7: The argument YY() is invalid. = 7: Singular convergence. (Hessian near the current iterate appears to be singular) = 8: False convergence. (Iterate appears to be converging to a noncritical point. Tolerances may be too small) = 9: Function evaluation limit reached. = 10: Iteration limit reached. = 63: F(X) cannot be computed at the initial X. = 65: The gradient could not be computed at X. [in] YY() Array YYp(LYY - 1) (LYY >= M) When returned with IRev = 1, the function value at X() should be given in YY() in the next call. [in,out] IRev Control variable for reverse communication. [in] Before first call, IRev should be initialized to zero. On succeeding calls, IRev should not be altered. [out] If IRev is not zero, set the required values to the specified variables or display the intermediate result as follows and call the routine again. = 0: Computation finished. See return code in Info. = 1: User should set the function values at X() in YY(). Do not alter any variables other than YY(). = 3: To be returned with IRev = 3 on each iteration if Iout = 1. Output the intermediate result (X(), NFcall, NFjcall, Niter, S, etc.). Do not alter any variables. [in] Iout (Optional) Whether the intermediate result output is necessary. (default = 0) = 0: Output is not necessary (never return with IRev = 3). = 1: Return on each iteration with IRev = 3 to output the intermediate results. (If other value is specified, Iout = 0 will be assumed) [out] Info2 (Optional) Sub-code for Info = 0. = 1: X convergence. = 2: Relative function convergence. = 3: Both X and relative function convergence. = 4: Absolute function convergence. [out] NFcall (Optional) Number of function evaluations with IRev = 1 including those for computing the covariance matrix. [out] NFjcall (Optional) Number of Jacobian evaluations with IRev = 2 including those for computing the covariance matrix. [out] Niter (Optional) Number of iterations. [out] S (Optional) Residual sum of squares at the obtained solution vector X(). [out] NFGcal (Optional) Invocation counter Nf which is used for subroutines F and Fj in N2g. [in] Rtol (Optional) Relative function convergence tolerance. (Eps <= Rtol <= 0.1) (default = 1e-10) (Eps shows the machine epsilon hereafter) (If Rtol < Eps or Rtol > 0.1, the default value will be used) [in] Atol (Optional) Absolute function convergence tolerance. (default = 1e-20) (If Atol < 0, the default value will be used) [in] MaxFcall (Optional) Maximum number of function evaluations of F. (default = 200) (If MaxFcall <= 0, the default value will be used) [in] MaxIter (Optional) Maximum number of iterations. (default = 150) (If MaxIter <= 0, the default value will be used) [in] Dtype (Optional) Choice of adaptive scaling. (Dtype = 0, 1 or 2) (default = 1) = 0: Disable adaptive scaling. (scale factor = 1) = 1: Enable adaptive scaling during all iterations. = 2: Enable adaptive scaling during the first iteration and scale factor is left unchanged thereafter. (For other values, the default value will be used) [in] Dfac (Optional) Factor for adaptive scaling (0 <= Dfac <= 1) (default = 0.6) A scale factor D(i) is chosen by adaptive scaling so that D(i)*X(i) has about the same magnitude for all i. Let D1(i) = max(||Ji||, Dfac*D(i)) where ||Ji|| is the 2-norm of the i-th column of Jacobian matrix, then D(i) is chosen as follows.   if D1(i) >= Dtol: D(i) = D1(i)   if D1(i) < Dtol: D(i) = D0 (If Dfac < 0 or Dfac > 1, the default value will be used) [in] Dtol (Optional) Tolerance for adaptive scaling. (Dtol > 0) (default = 1.0e-6) (If Dtol <= 0, the default value will be used) [in] D0 (Optional) Initial value for adaptive scaling. (D0 > 0) (default = 1) (If D0 <= 0, the default value will be used) [in] Tuner1 (Optional) Parameter to check for false convergence. (0 <= Tuner1 <= 0.5) (default = 0.1) (If Tuner1 < 0 or Tuner1 > 0.5, the default value will be used) [in] Xctol (Optional) X convergence tolerance. (0 <= Xctol <= 1) (default = Eps^(1/2)) (If Xctol < 0 or Xctol > 1, the default value will be used) [in] Xftol (Optional) False convergence tolerance. (0 <= Xftol <= 1) (default = 100*Eps) (If Xftol < 0 or Xftol > 1, the default value will be used) [in] Lmax0 (Optional) Maximum 2-norm allowed for scaled very first step. (Lmax0 > 0) (default = 1) (If Lmax0 <= 0, the default value will be used) [in] Lmaxs (Optional) [in] Sctol (Optional) Lmaxs and Sctol are the singular convergence test parameters. (Lmaxs > 0, 0 <= Sctol <= 1) (default: Lmaxs = 1, Sctol = 1e-10) If the function reduction predicted for a step of length bounded by Lmaxs is less than Sctol*abs(f), returns with Info = 7 (f is the function value at the start of the current iteration). (If Lmaxs <= 0, the default value will be used) (If Sctol < 0 or Sctol > 1, the default value will be used) [in] Dltfdj (Optional) Step size used to compute finite difference Jacobian approximation is chosen as follows. (Eps <= Dltfdj <= 1) (default = Sqrt(Eps))   Dltfdj*max(|X(I)|, 1/D(I)) (If Dltfdj < Eps or Dltfdj > 1, the default value will be used) Reference netlib/port Example Program Approximate the following data with model function f(x) = c1*(1 - exp(-c2*x)). Determine two parameters c1 and c2 by the nonlinear least squares method. f(x) x 10.07 77.6 29.61 239.9 50.76 434.8 81.78 760.0 The initial estimates of the solution are c1 = 500 and c2 = 0.0001. Lower and upper bounds on solution are 100 <= c1 <= 500 and 0 <= c2 <= 0.1. Sub FN2f(M As Long, N As Long, X() As Double, Nf As Long, Fvec() As Double) Dim Xdata(3) As Double, Ydata(3) As Double, I As Long Ydata(0) = 10.07: Xdata(0) = 77.6 Ydata(1) = 29.61: Xdata(1) = 239.9 Ydata(2) = 50.76: Xdata(2) = 434.8 Ydata(3) = 81.78: Xdata(3) = 760 For I = 0 To M - 1 Fvec(I) = Ydata(I) - X(0) * (1 - Exp(-Xdata(I) * X(1))) Next End Sub Sub Ex_N2fb_r() Const M = 4, N = 2 Dim X(N - 1) As Double, B(1, N - 1) As Double, Info As Long Dim YY(M - 1) As Double, IRev As Long X(0) = 500: X(1) = 0.0001 B(0, 0) = 100: B(1, 0) = 500 B(0, 1) = 0: B(1, 1) = 0.1 IRev = 0 Do Call N2fb_r(M, N, X(), B(), Info, YY(), IRev) If IRev = 1 Then Call FN2f(M, N, X(), 0, YY()) End If Loop While IRev <> 0 Debug.Print "C1, C2 =", X(0), X(1) Debug.Print "Info =", Info End Sub Example Results C1, C2 = 241.084897031558 5.44942231585591E-04 Info = 0