funct must evaluate the function

F (x)

and its first derivatives

\frac{\partial F}{\partial x_{j}}

at a specified point. (However, if you do not wish to calculate

F

or its first derivatives at a particular

x

, there is the option of setting a parameter to cause e04kd to terminate immediately.)

Syntax

C#
public delegate void E04KD_FUNCT( ref int iflag, int n, double[] xc, ref double fc, double[] gc )

Visual Basic
Public Delegate Sub E04KD_FUNCT ( _ ByRef iflag As Integer, _ n As Integer, _ xc As Double(), _ ByRef fc As Double, _ gc As Double() _ )

Visual C++
public delegate void E04KD_FUNCT( int% iflag, int n, array<double>^ xc, double% fc, array<double>^ gc )

F#
type E04KD_FUNCT = delegate of iflag : int byref * n : int * xc : float[] * fc : float byref * gc : float[] -> unit

iflag: Type: System..::..Int32%
On entry: will have been set to $1$ or $2$ . The value $1$ indicates that only the first derivatives of $F$ need be supplied, and the value $2$ indicates that both $F$ itself and its first derivatives must be calculated.
On exit: if it is not possible to evaluate $F$ or its first derivatives at the point given in xc (or if it is wished to stop the calculations for any other reason) you should reset iflag to a negative number and return control to e04kd. e04kd will then terminate immediately, with ifail set to your setting of iflag.

xc: Type: array<System..::..Double>[]()[][]
On entry: the point $x$ at which the $\frac{\partial F}{\partial x_{j}}$ , or $F$ and the $\frac{\partial F}{\partial x_{j}}$ , are required.

fc: Type: System..::..Double%
On exit: unless $iflag = 1$ on entry or iflag is reset, funct must set fc to the value of the objective function $F$ at the current point $x$ .

gc: Type: array<System..::..Double>[]()[][]
On exit: unless funct resets iflag, it must set $gc [j - 1]$ to the value of the first derivative $\frac{\partial F}{\partial x_{j}}$ at the point $x$ , for $j = 1, 2, \dots, n$ .

See Also