A penalty function to experiment with different windows and calculation methods

penalty.c

// experimental penalty() function for n7.c
// Rename the existing function to x_penalty() or something similar so that it won't be executed
// and then add the following function

static double
penalty(int k, int s, int h, int h2, int h3)
{
	double	t, d, p1, p2, p3 ;

	int	scaletype, calctype ;

// Change the values of scaletype and calctype to select the range of acceptable space sizes and the demerits calculation you want,
// then recompile troff.  The scaletype and calctype can be matched as desired.
//
// The hyphenation penalty should be adjusted externally to reasonably compare the calctypes, although there is no direct match.
// If hypp 50 is assumed to be the standard number, the hypp value used with the Tex calculation (2) should be about 25, and
// for the two-stage curve (4) hypp should be about 35.
//
// In Heirloom's calculations, hypp 50 applies a penalty of the same value as a marginally bad word space at the edge of the
//   acceptable range (0 or 19.2 troff space units, with the desired space size of 12 units).  Compare with TeX's value 50,
//   which applies a penalty similar to that of a word space that is a little worse than the "normal" range (10 to 15 units).

	scaletype = 1 ;	// 1=Heirloom (0-19.2), 2=tex (8-18), 3=symmetrical (6-18), 4=intermediate (7-18)

	calctype = 1 ;	// 1=Heirloom, 2=tex14, 3=kp81, 4=two-stage quadratic, 5=initial proposal

// ----------------

	t = nel - k;

	if (scaletype <= 1 || scaletype > 4)
		t = t >= 0 ? t * 5 / 3 : -t ;	// Heirloom's original line

	else if (scaletype == 2)
		t = t >= 0 ? t * 2 : t * -3 ;	// TeX

	else if (scaletype == 3)
		t = t >= 0 ? t * 2 : t * -2 ;	// symmetrical

	else if (scaletype == 4)
		t = t >= 0 ? t * 2 : t * -2.5 ;	// intermediate

// -----------------

	if (ad && !admod) {
		d = s;
//		if (k - s && (letsps || lshmin || lshmax))
//			d += (double)(k - s) / 100;
		if (d)
			t /= d;		// rj 
	} else
		t /= nel / 10;

	p1 = p2 = p3 = 0 ;

	if (h && hypp)
		p1 = hypp ;
	if (h2 && hypp2)
		p2 = hypp2 ;
	if (h3 && hypp3)
		p3 = hypp3 ;


// demerits calculations  ------

	if (calctype <= 1 || calctype > 5) {		// heirloom
		t = t + p1 + p2 + p3 ;	
		t = t * t * t ;	

	} else if (calctype == 2) {			// TeX14 (after 1982) (adapted)
		t = 1 + 100 * t * t * t ;
		t = t * t ;
		t /= 10000 ;
		t += p1 * p1 + p2 * p2 + p3 * p3 ;

	} else if (calctype == 3) {			// TeX from KP-81 (adapted)
		t = 1 + 100 * t * t * t + p1 ;
		t = t * t  ;
		t /= 10000 ;
		t += p2 * p2 + p3 * p3 ;

	} else if (calctype == 4) {			// two-stage curve
		t = t * t ;				// quadratic in-band
		if (t > 1)
			t = t * t * t ;			// but same out-of-band as the TeX14 curve
		t += p1 * p1 + p2 * p2 + p3 * p3 ;

	} else if (calctype == 5) {			// initial proposal
		t = t * t * t ;
		t = t * t ;
		t += (p1 + p2 + p3) * (p1 + p2 * p3) ;
	}

// -----------------

	if (t > MAXPENALTY)
		t = MAXPENALTY;

	return t;
}