* PR 07-Sep-94.         (sg26.3: STB-25)
program define _jprfptp /* determines whether m=2 curve is monotonic. */
	version 3.1
	local p1 `1'
	local p2 `2'
	local gamma `3' /* beta_2/beta_1 */
	local small 1e-6
	if `p1'>`p2' { /* can occur with 1 fixpower and 1 variable power */
		local temp `p1'
		local p1 `p2'
		local p2 `temp'
	}
	local gp1=`gamma'/`p1'
	local gp2=`gamma'*`p2'
	local xpk .
	if abs(`p1')<`small' {
		if abs(`p2')<`small' { 		/* (0,0) */
			local xpk=-1/(2*`gamma')
		}
		else {				/* (0,p2) */
			if `gp2'<0 { local xpk=-log(-`gp2')/`p2' }
		}
	}
	else if abs(`p2')<`small' {		/* (p1,0) */
		if `gp1'<0 { local xpk=log(-`gp1')/`p1' }
	}
	else {
		if abs(`p2'-`p1')<`small' {	/* (p1,p1) */
			local xpk=-1/`p1'-1/`gamma'
		}
		else {				/* (p1,p2) */
			local gp12=`p2'*`gp1'
			if `gp12'<0 {
				local xpk=log(-`gp12')/(`p1'-`p2')
			}
		}
	}
	global S_26 `xpk'
end