rkdumb.txt

《Delphi常用数值算法集》的配书源码

procedure RKDUMB(VSTART:array of real; NVAR:integer; X1, X2:real;
                            NSTEP:integer;var XX:array of real; Y:matrx2);
var
    V,DV:array[0..10] of real;  I,K:integer;  X,H:real;
begin
    For I:=1 To NVAR do
    begin
        V[I]:=VSTART[I];
        Y[I, 1]:=V[I];
    end; 
    XX[1]:=X1;
    X:=X1;
    H:=(X2 - X1) / NSTEP;
    For K:=1 To NSTEP do
    begin
        DERIVS(X, V, DV);
        RK4(V, DV, NVAR, X, H, V);
        If X + H = X Then
        begin
            ShowMessage('Stepsize not signficant in RKDUMB.');
            Exit;
        end;
        X:=X + H;
        XX[K + 1]:=X;
        For I:=1 To NVAR do
            Y[I, K + 1]:=V[I];
    end;
end;