间距问题不会影响公式正确性,但会影响美观。以下是关于间距问题的一些tips
(1)不要在指数或积分上下限中使用 {frac},最好将分数写成水平格式:
\begin{array} {cc}
\text{Bad} & \text{Better} \\[2ex]
\hline
e^{i \frac{ \pi}{2}} & e^{i \pi / 2} \\[2ex]
\int_{- \frac{ \pi}{2}}^{\frac{ \pi}{2}} \sin x \, dx & \int_{- \pi / 2}^{\pi / 2} \sin x \, dx \\[2ex]
\end{array}
\begin{array} {cc}
\text{Bad} & \text{Better} \\[2ex]
\hline
e^{i \frac{ \pi}{2}} & e^{i \pi / 2} \\[2ex]
\int_{- \frac{ \pi}{2}}^{\frac{ \pi}{2}} \sin x \, dx & \int_{- \pi / 2}^{\pi / 2} \sin x \, dx \\[2ex]
\end{array}
(2)|符号在用作分隔符时,常常会出现间距问题。因此,最好用 \mid 来代替它:
\begin{array} {cc}
\text{Bad} & \text{Better} \\[2ex]
\hline
\{x | x^2 \in \Bbb Z\} & \{x \mid x^2 \in \Bbb Z\} \\[2ex]
\end{array}
\begin{array} {cc}
\text{Bad} & \text{Better} \\[2ex]
\hline
\{x | x^2 \in \Bbb Z\} & \{x \mid x^2 \in \Bbb Z\} \\[2ex]
\end{array}
(3)双重、三重积分中,不要使用 \int\int 或 \int\int\int,而用 \iint 和 \iiint 代替:
\begin{array} {cc}
\text{Bad} & \text{Better} \\[2ex]
\hline
\int\int_S \, dy \, dx & \iint_S f(x) \, dy \, dx \\[2ex]
\int\int\int_V \, dy \, dx & \iiint_V f(x) \, dz \, dy \, dx \\[2ex]
\end{array}
\begin{array} {cc}
\text{Bad} & \text{Better} \\[2ex]
\hline
\int\int_S \, dy \, dx & \iint_S f(x) \, dy \, dx \\[2ex]
\int\int\int_V \, dy \, dx & \iiint_V f(x) \, dz \, dy \, dx \\[2ex]
\end{array}
(3)多重积分后面的几个自变量微分之间,用 \, 隔开,否则会挤在一起:
\begin{array} {cc}
\text{Bad} & \text{Better} \\[2ex]
\hline
\iiint_V f(x) dz dy dx & \iiint_V f(x) \, dz \, dy \, dx \\[2ex]
\end{array}
\begin{array} {cc}
\text{Bad} & \text{Better} \\[2ex]
\hline
\iiint_V f(x) dz dy dx & \iiint_V f(x) \, dz \, dy \, dx \\[2ex]
\end{array}