scrsho.cpp

Visual C++ 常用数值算法集 源代码

void scrsho()
{
	int iscr,jscr,j,i,jz;
	char scr[61][22],blank,zero,yy,xx,ff;
	double x,dx,x1,x2,ybig,ysml,dyj,y[60];
    iscr = 60;
    jscr = 21;
    blank = ' ';
    zero = '-';
    yy = '1';
    xx = '-';
    ff = 'x';
    //enter x1,x2 [x1=x2 to stop]
    x1 = -5.0; 
    x2 = 5.0 ;
    if (x1 == x2) _c_exit();
    for (j = 1 ; j<=jscr; j++)
	{
        scr[1][j] = yy;
        scr[iscr][j] = yy;
    }
    for (i = 2; i<=iscr - 1; i++)
	{
        scr[i][1] = xx;
        scr[i][jscr] = xx;
        for (j = 2; j<=(jscr - 1); j++)
		{
            scr[i][ j] = blank;
        }
    }
    dx = double(x2 - x1) / double(iscr - 1);
    x = x1;
    ybig = 0.0 ;
    ysml = ybig;
    for (i = 1; i<=iscr; i++)
	{
        y[i] = func(x);
        if (y[i] < ysml) ysml = y[i];
        if (y[i] > ybig) ybig = y[i];
        x = x + dx;
    }
    if (ybig == ysml) ybig = ysml + 1.0; 
    dyj = (jscr- 1) /(ybig - ysml);
    jz = int(1 - ysml * dyj);
    for (i = 1; i<= iscr; i++)
	{
        scr[i][jz] = zero;
        j = int(1 + (y[i] - ysml) * dyj);
        scr[i][j] = ff;
    }
    cout<<ybig;
    cout<< " ";
    for (i = 1; i<=iscr; i++)
	{
        cout<< scr[i][jscr];
    }
    cout<<endl;
    for (j = jscr - 1; j>=2; j--)
	{
		cout<< "         ";
        for (i = 1; i<=iscr; i++)
		{
           cout<< scr[i][j];
		}
        cout<<endl;
    }
    cout<<ysml, "  .      ";
    cout<< " ";
    for (i = 1; i<=iscr; i++)
    {
        cout<< scr[i][1];
    }
    cout<<endl;
    cout<< "         ";
    cout<< x1<< "                                      ";
    cout<< x2<< "  .       "<<endl;
}