The appearance of equations is controlled by a large number of parameters. These can be set using the
command.
Possible parameters are as follows. Values are in units of hundredths of an em unless otherwise stated. These descriptions are intended to be expository rather than definitive.
minimum_size
eqn will not set anything at a smaller point-size than this. The value is in points.
fat_offset
The fat primitive emboldens an equation by overprinting two copies of the equation horizontally offset by this amount.
over_hang
A fraction bar will be longer by twice this amount than the maximum of the widths of the numerator and denominator; in other words, it will overhang the numerator and denominator by at least this amount.
accent_width
When bar or under is applied to a single character, the line will be this long. Normally, bar or under produces a line whose length is the width of the object to which it applies; in the case of a single character, this tends to produce a line that looks too long.
delimiter_factor
Extensible delimiters produced with the left and right primitives will have a combined height and depth of at least this many thousandths of twice the maximum amount by which the sub-equation that the delimiters enclose extends away from the axis.
delimiter_shortfall
Extensible delimiters produced with the left and right primitives will have a combined height and depth not less than the difference of twice the maximum amount by which the sub-equation that the delimiters enclose extends away from the axis and this amount.
null_delimiter_space
This much horizontal space is inserted on each side of a fraction.
script_space
The width of subscripts and superscripts is increased by this amount.
thin_space
This amount of space is automatically inserted after punctuation characters.
medium_space
This amount of space is automatically inserted on either side of binary operators.
thick_space
This amount of space is automatically inserted on either side of relations.
x_height
The height of lowercase letters without ascenders such as `x'.
axis_height
The height above the baseline of the center of characters such as `+' and `−'. It is important that this value is correct for the font you are using.
default_rule_thickness
This should set to the thickness of the \(ru character, or the thickness of horizontal lines produced with the \D escape sequence.
num1
The over command will shift up the numerator by at least this amount.
num2
The smallover command will shift up the numerator by at least this amount.
denom1
The over command will shift down the denominator by at least this amount.
denom2
The smallover command will shift down the denominator by at least this amount.
sup1
Normally superscripts will be shifted up by at least this amount.
sup2
Superscripts within superscripts or upper limits or numerators of smallover fractions will be shifted up by at least this amount. This is usually less than sup1.
sup3
Superscripts within denominators or square roots or subscripts or lower limits will be shifted up by at least this amount. This is usually less than sup2.
sub1
Subscripts will normally be shifted down by at least this amount.
sub2
When there is both a subscript and a superscript, the subscript will be shifted down by at least this amount.
sup_drop
The baseline of a superscript will be no more than this much amount below the top of the object on which the superscript is set.
sub_drop
The baseline of a subscript will be at least this much below the bottom of the object on which the subscript is set.
big_op_spacing1
The baseline of an upper limit will be at least this much above the top of the object on which the limit is set.
big_op_spacing2
The baseline of a lower limit will be at least this much below the bottom of the object on which the limit is set.
big_op_spacing3
The bottom of an upper limit will be at least this much above the top of the object on which the limit is set.
big_op_spacing4
The top of a lower limit will be at least this much below the bottom of the object on which the limit is set.
big_op_spacing5
This much vertical space will be added above and below limits.
baseline_sep
The baselines of the rows in a pile or matrix will normally be this far apart. In most cases this should be equal to the sum of num1 and denom1.
shift_down
The midpoint between the top baseline and the bottom baseline in a matrix or pile will be shifted down by this much from the axis. In most cases this should be equal to axis_height.
column_sep
This much space will be added between columns in a matrix.
matrix_side_sep
This much space will be added at each side of a matrix.
draw_lines
If this is non-zero, lines will be drawn using the \D escape sequence, rather than with the \l escape sequence and the \(ru character.
body_height
The amount by which the height of the equation exceeds this will be added as extra space before the line containing the equation (using \x). The default value is 85.
body_depth
The amount by which the depth of the equation exceeds this will be added as extra space after the line containing the equation (using \x). The default value is 35.
nroff
If this is non-zero, then ndefine will behave like define and tdefine will be ignored, otherwise tdefine will behave like define and ndefine will be ignored. The default value is 0 (This is typically changed to 1 by the eqnrc file for the ascii, latin1, utf8, and cp1047 devices.)
A more precise description of the role of many of these parameters can be found in Appendix H of The book.