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diff --git a/sys/gio/glabax/glbloglab.x b/sys/gio/glabax/glbloglab.x
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+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+include	<mach.h>
+include	<gset.h>
+include	<gio.h>
+include	"glabax.h"
+
+define	SZ_MANTISSA	3		# "10" or "-10"
+define	SZ_EXPONENT	4		# largest is "-999"
+
+
+# GLB_LOGLAB -- Draw a tick label in log units at the given position.
+# A log tick is a power of ten, e.g.  10^2, where the ^ signifies that
+# the 2 is to be drawn one half character height higher than the 10.
+
+procedure glb_loglab (gp, sx, sy, val, fmt, scaling)
+
+pointer	gp			# graphics descriptor
+real	sx, sy			# NDC coords of label
+real	val			# value to be encoded (not the log of)
+char	fmt[ARB]		# tick label gtext format (justification)
+int	scaling			# type of scaling on axis
+
+bool	zero
+char	mantissa[SZ_MANTISSA]
+char	exponent[SZ_EXPONENT]
+int	len_mantissa, len_exponent, ip, hj, vj
+real	logval, char_height, char_width, left, xpos, ypos, txsize
+
+bool	fp_equalr()
+real	elogr(), gstatr(), ggetr()
+int	strlen(), strmatch(), itoc()
+
+begin
+	# Compute the log value to be encoded.
+	if (scaling == LOG)
+	    logval = log10 (val)
+	else {
+	    logval = elogr (val)
+	    zero = fp_equalr (logval, 0.0)
+	}
+
+	txsize = gstatr (gp, G_TXSIZE)
+
+	# Get char height and width in NDC coords.
+	char_height = ggetr (gp, "ch")
+	if (char_height < EPSILON)
+	    char_height = DEF_CHARHEIGHT
+	char_height = char_height * txsize
+
+	char_width = ggetr (gp, "cw")
+	if (char_width < EPSILON)
+	    char_width = DEF_CHARWIDTH
+	char_width = char_width * txsize
+
+	# Encode the mantissa and exponent strings.
+	if (zero) {
+	    call strcpy ("0", mantissa, SZ_MANTISSA)
+	} else if (logval < 0 && scaling == ELOG) {
+	    call strcpy ("-10", mantissa, SZ_MANTISSA)
+	    logval = abs (logval)
+	} else
+	    call strcpy ("10", mantissa, SZ_MANTISSA)
+
+	len_mantissa = strlen (mantissa)
+	if (zero)
+	    len_exponent = 0
+	else
+	    len_exponent = itoc (nint(logval), exponent, SZ_EXPONENT)
+
+	# Determine type of horizontal justification required.
+	ip = strmatch (fmt, "hj=")
+	if (ip <= 0)
+	    hj = 'c'
+	else
+	    hj = fmt[ip]
+
+	# Determine type of vertical justification required.
+	ip = strmatch (fmt, "vj=")
+	if (ip <= 0)
+	    vj = 'c'
+	else
+	    vj = fmt[ip]
+
+	# On devices with adjustable character sizes the most pleasing results
+	# are obtained if the digits "10" are nicely aligned on the vertical
+	# axis, regardless of the actual number of characters in the exponent
+	# string, minus signs etc (this type of alignment is more natural
+	# because the exponent is printed at half size).  Hence if we are on
+	# a vertical axis (hj != c) fix the number of characters in the two
+	# strings so that the alignment comes out the same regardless of the
+	# actual number of chars in either field.  The length of the exponent
+	# field is not completely fixed, rather we allow a little more space
+	# if the exponent is large.  For small exponents len_exponent=1.
+
+	if (hj != 'c') {
+	    len_mantissa = 2
+	    len_exponent = (len_exponent + 1) / 2
+	}
+
+	# Compute XPOS, the NDC X coord of the point halfway between the
+	# last char of the mantissa and the first char of the exponent.
+
+	switch (hj) {
+	case 'l':
+	    left = sx
+	case 'r':
+	    left = sx - (len_mantissa + len_exponent) * char_width
+	default:
+	    left = sx - ((len_mantissa + len_exponent) * char_width) / 2.0
+	}
+
+	xpos = left + len_mantissa * char_width
+
+	# Compute YPOS, the NDC Y coord of the center of a mantissa character
+	# and of the bottom of an exponent character.  Using the same coordinate
+	# to address both positions makes the label come out the same regardless
+	# of the plot magnification, even on a device where the character size
+	# is fixed by the hardware.
+
+	switch (vj) {
+	case 'b':
+	    ypos = sy + char_height / 2.0
+	case 't':
+	    ypos = sy - char_height / 2.0
+	default:
+	    ypos = sy
+	}
+
+	# Draw the mantissa.
+	call gtext (gp, xpos, ypos, mantissa, "hj=r,vj=c")
+
+	# Draw the exponent if there is one.
+	if (!zero) {
+	    call gsetr (gp, G_TXSIZE, txsize / 2.0)
+	    call gtext (gp, xpos, ypos, exponent, "hj=l;vj=b")
+	    call gsetr (gp, G_TXSIZE, txsize)
+	}
+end