MODULE TestSplines;
FROM CubicSplines IMPORT Spline,MakeSpline,EvalSpline,DerivSpline;
FROM DIG IMPORT 
    (* TYPE *) GArrowHead, GLineType, GFontType, GJustType, GDeviceType,
               GColorType,
    (* VAR  *) GDevice   ,
    (* PROC *) GSlope, GInitDevice,
               GErase, GWindow, GMapWindow, GMove, GDraw,
               GBox, GCircle, GEllipse, GArc, GLine, GPolyLine, GArrow,
               GSpline, GSetLinePattern, GSetFont, GSetCharSize,
               GCharCellSize, GText, GSetColor, GWrapUp;
FROM FileSystem IMPORT Done, Open, Close, Reset;
FROM InOut IMPORT in, WriteString,WriteReal,WriteLn,ReadReal,ReadLn,ReadCard,
                  Read;

CONST max = 20;
VAR
    status : BOOLEAN;
    pi : REAL;
    i  : CARDINAL;
    n  : CARDINAL;
    x,y : ARRAY [0..max] OF REAL;
    npt : CARDINAL;
    xv, yv : ARRAY [0..100] OF REAL;
    dev   : CHAR;
    dx : REAL;
    s  : Spline;
BEGIN
    Open( in, "Test.dat", FALSE );
    IF NOT Done( ) THEN
        WriteString("Touble opening Test.dat ");
        WriteLn;
        HALT;
    END;
    Reset( in );
    ReadCard( n );
    ReadLn;
    IF n-1 > max THEN
        WriteString("n > max , set n to max ");
        WriteLn;
        n := max+1;
    END;
    FOR i := 0 TO n-1 DO
        ReadReal( x[i] ); ReadReal( y[i] ); ReadLn;
    END;
    Read( dev ); ReadLn;
    IF dev = 'v' THEN GDevice := vt125
    ELSIF dev = 'h' THEN GDevice := hp
    ELSIF dev = 't' THEN GDevice := tek
    ELSE
        WriteString("strange device " );
        WriteLn;
        HALT;
    END;
    Close( in );
    
    status := MakeSpline( x, y, n, s );
    npt := 51;
    dx := ( x[n-1] - x[0] )/ FLOAT( npt-1 );
    FOR i :=  1 TO npt DO
        xv[i-1] := x[0] + FLOAT( i-1 )*dx;
        status := EvalSpline( xv[i-1], s, yv[i-1] );
    END;
    GInitDevice( 0.0, 0.0, 11.0, 8.5, 1200, "test.gf" );
    GErase( );
    GMapWindow( 0.0, -1.0, 6.0, 1.25 );
    GSetColor( Ggreen );
    GPolyLine( x, y, INTEGER(n));
    GPolyLine( xv, yv, INTEGER(npt) );
    GArrow( xv[npt-2],yv[npt-2], xv[npt-1],yv[npt-1], RightHead );
    GWrapUp( );

END TestSplines.