将矩阵条目刷新到左侧

将矩阵条目刷新到左侧

所以我有以下代码

\begin{dmath}
  P_1=\left\{\begin{matrix}
{P_E} + K(1 - {e^{ - rT}}) - S(1 - {e^{ - \delta T}})\\
- KI(0,T,S,{B_{11}},{b_{11}}, - 1,r)\\
+ SI(0,T,S,{B_{11}},{b_{11}},1,\delta )\;\text{if }\;S > {B_{11}}\\
K - S\quad \text{if } \;S \le {B_{11}}
\end{matrix}\right.
\end{dmath}


\begin{dmath}
P_2=\left\{\begin{matrix}
{P_E} + K(1 - {e^{ - rT}}) - S(1 - {e^{ - \delta T}})\\
- KI(0,T/2,S,{B_{21}},{b_{21}}, - 1,r)\\
+ SI(0,T/2,S,{B_{21}},{b_{21}},1,\delta )\\
- KI(T/2,T,S,{B_{21}},{b_{21}}, - 1,r)\\
+ SI(T/2,T,S,{B_{21}},{b_{21}},1,\delta )\quad \text{if }\;S > {B_{22}}\\
K - S\quad \text{if }\;S \le {B_{22}}.
\end{matrix}\right.
\end{dmath}

\begin{dmath}   
P_3=\left\{\begin{matrix}
{P_E} + K(1 - {e^{ - rT}}) - S(1 - {e^{ - \delta T}})\\
- KI(0,T/3,S,{B_{33}},{b_3}, - 1,r)\\
+ SI(0,T/3,S,{B_{33}},{b_3},1,\delta )\\
- KI(T/3,2T/2,S,{B_{32}},{b_{32}}, - 1,r)\\
+ SI(T/3,2T/3,S,{B_{32}},{b_{32}},1,\delta )\\
- KI(2T/3,T,S,{B_{31}},{b_{31}}, - 1,r)\\
+ SI(2T/3,T,S,{B_{31}},{b_{31}},1,\delta )\quad \text{if }\;S > {B_{33}}\\
K - S\quad \text{if }\;S \le {B_{33}}.\\
\end{matrix}\right.
\end{dmath}

不幸的是,这会产生以下图片

在此处输入图片描述

我希望它看起来更像这样在此处输入图片描述

答案1

我会使用包cases中的环境amsmath。我不知道你的matrix环境dmath来自哪里。

我认为您所体验到的额外间距是由于\left\{

例子:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\noindent
\begin{equation}
P_{1}=
\begin{cases}
P_E + K(1 - {e^{ - rT}}) - S(1 - {e^{ - \delta T}})\\
{}- KI(0,T,S,{B_{11}},{b_{11}}, - 1,r)\\
{}+ SI(0,T,S,{B_{11}},{b_{11}},1,\delta )\quad\text{if}\; S > {B_{11}}\\
K - S\quad \text{if}\; S \le {B_{11}}.
\end{cases}
\end{equation}

\begin{equation}
P_{2}=
\begin{cases}
P_E + K(1 - {e^{ - rT}}) - S(1 - {e^{ - \delta T}})\\
{}- KI(0,T/2,S,{B_{21}},{b_{21}}, - 1,r)\\
{}+ SI(0,T/2,S,{B_{21}},{b_{21}},1,\delta )\\
{}- KI(T/2,T,S,{B_{21}},{b_{21}}, - 1,r)\\
{}+ SI(T/2,T,S,{B_{21}},{b_{21}},1,\delta )\quad \text{if}\; S > {B_{22}}\\
K - S\quad \text{if}\; S \le {B_{22}}.
\end{cases}
\end{equation}

\begin{equation}
P_{3}=
\begin{cases}
P_E + K(1 - {e^{ - rT}}) - S(1 - {e^{ - \delta T}})\\
{}- KI(0,T/3,S,{B_{33}},{b_3}, - 1,r)\\
{}+ SI(0,T/3,S,{B_{33}},{b_3},1,\delta )\\
{}- KI(T/3,2T/2,S,{B_{32}},{b_{32}}, - 1,r)\\
{}+ SI(T/3,2T/3,S,{B_{32}},{b_{32}},1,\delta )\\
{}- KI(2T/3,T,S,{B_{31}},{b_{31}}, - 1,r)\\
{}+ SI(2T/3,T,S,{B_{31}},{b_{31}},1,\delta )\quad \text{if}\; S > {B_{33}}\\
K - S\quad \text{if}\; S \le {B_{33}}.
\end{cases}
\end{equation}
\end{document}

在此处输入图片描述

答案2

如果我正确理解了你的意图,你正在追求这样的事情:

以下代码的输出

代码:

% My standard header for TeX.SX answers:
\documentclass[a4paper]{article} % To avoid confusion, let us explicitly 
                                 % declare the paper format.

\usepackage[T1]{fontenc}         % Not always necessary, but recommended.
% End of standard header.  What follows pertains to the problem at hand.

\usepackage{mathtools}



\begin{document}

It's always best to start with some text.
\begin{align}
    P_{1} &=
        \begin{cases*}
            \begin{aligned}[b]
                P_{E} &+ K(1 - e^{-rT}) - S(1 - e^{-\delta T})\\
                & - KI(0,T,S,B_{11},b_{11},-1,r)\\
                & + SI(0,T,S,B_{11},b_{11},1,\delta )
            \end{aligned}
            & if $S > B_{11}$, \\
            K - S & if $S \le B_{11}$.
        \end{cases*}
    \\
    P_{2} &=
        \begin{cases*}
            \begin{aligned}[b]
                P_{E} &+ K(1 - e^{-rT}) - S(1 - e^{-\delta T})\\
                & - KI(0,T/2,S,B_{21},b_{21},-1,r)\\
                & + SI(0,T/2,S,B_{21},b_{21},1,\delta )\\
                & - KI(T/2,T,S,B_{21},b_{21},-1,r)\\
                & + SI(T/2,T,S,B_{21},b_{21},1,\delta )
            \end{aligned}
            & if $S > B_{22}$, \\
            K - S & if $S \le B_{22}$.
        \end{cases*}
    \\
    P_{3} &=
        \begin{cases*}
            \begin{aligned}
                P_{E} &+ K(1 - e^{-rT}) - S(1 - e^{-\delta T})\\
                & - KI(0,T/3,S,B_{33},b_{3},-1,r)\\
                & + SI(0,T/3,S,B_{33},b_{3},1,\delta )\\
                & - KI(T/3,2T/2,S,B_{32},b_{32},-1,r)\\
                & + SI(T/3,2T/3,S,B_{32},b_{32},1,\delta )\\
                & - KI(2T/3,T,S,B_{31},b_{31},-1,r)\\
                & + SI(2T/3,T,S,B_{31},b_{31},1,\delta )
            \end{aligned}
            & if $S > B_{33}$, \\
            K - S & if $S \le B_{33}$.
        \end{cases*}
\end{align}
Text after the equations.

\end{document}

注意事项:

  • mathtools包(也会自动加载amsmath)提供了一个cases*环境,该环境以文本模式(而不是数学模式)排版第二列。还有其他选择:请参阅包手册第 18 页mathtools

  • 我使用了一个aligned带有可选参数的环境 [b]来包装属于同一逻辑分支的长公式(我再说一遍,如果我理解正确的话)。

  • 我还去掉了很多多余的牙套。

  • 作为一个“特征”(;-),最后一个等式通过示例展示了该[b] 论点的用途……

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