Latex: The ordinal of a formula

1. Sort units

In the text class book or report, the row formula is in the order of the chapter, that is, each new chapter starts, the formula ordinal counter equation is cleared. For example, the 1th Chapter 3rd formula ordinal is (1.3), 2nd Chapter 1th Formula ordinal is (2.1). There are several sections in a chapter, and if there are many formulas in each section, it is difficult to tell which section the formula belongs to. If you want the formula to be sorted in sections, you can add the sort units command provided by the Formula macro package in the introduction: \numberwithin{equation}{section}

This adds the section number to the ordinal of all formulas. For example, the sequence number of the 2nd formula in the 1th Chapter 3rd is: (1.3.2). In the text class article, the row formula sequence number is in the full text as the sorting unit, if you want to change the section as the sorting unit, you can also use the above sorting Unit command.

2. Cancellation and substitution

The formula environment with asterisks and the split and cases formula environments do not give formula numbers, and other formulas without models can automatically provide a sequence number for the formula. But sometimes you want some formulas in the formula group to have ordinal numbers, some not, and some to be labeled otherwise, you need to use the following ordinal set command.

\eqno{Label}	The system-supplied ordinal setting command, which immediately follows the formula line in the form of a equation* environment or \[...\], manually sets the label to the right of the formula. The label can be any text
\leqno{Label}	Acting on the same \eqno, just label the left side of the formula. \eqno and \leqno cannot be used in a formula at the same time
\nonumber	The system-supplied cancellation sequence command. You can cancel the line formula by inserting it before the newline command \ \ To make it no ordinal
\notag	Formula macro Package provides an ordinal cancellation command, using the same method and function as the \nonumber command
\tag{Label}	The Formula macro package provides the ordinal setting command, which is inserted before the line break command \ \, to sort the line formula and replace the ordinal with a (label). The command can also be used with the formula line in an asterisk formula environment to have (label)
\tag*{Label}	The effect is the same as \tag, except that there are no parentheses on either side of the label

2.1 The sequence number of the matrix equation is changed to manual marking, and as to the left side of the equation

Code:

$$\left (\BEGIN{ARRAY}{LCR}
a_{11}& a_{12} & a_{13}\\
A_{21} & A_{22} & A_{23}
\end{array}\right) =0 \leqno[a.1] $$

The formula obtained is as follows:

Latex: The ordinal of a formula