How to draw box for my math equation in latex

[snshusat161]

I want to enclose my final equation inside a box but i find no way to do that in latex. please help me out as soon as possible.

Thanks!

 

[yenchin]

Use "\boxed{}"

 

[snshusat161]

Not working

My latex code is

\begin{flalign*}
E_1 & = \frac{e_{1max}}{\sqrt{2}}\\
& = \frac{N_1.{\phi}_m.w}{\sqrt{2}}\\
& = \frac{N_1{\phi}_m.2\pi.f}{\sqrt{2}}\\
\\
E_1 & = 4.44 N_1.{\phi}_m.f\\
\\
E_1 & = 4.44 N_1.B_m.A.f
\end{flalign*}

and after using \boxed in

E_1 & = 4.44 N_1.B_m.A.f

I get the following error:

This is pdfTeX, Version 3.1415926-1.40.11 (MiKTeX 2.9)
entering extended mode
(E:/notes/test.tex
LaTeX2e <2009/09/24>
Babel <v3.8l> and hyphenation patterns for english, afrikaans, ancientgreek, ar
abic, armenian, assamese, basque, bengali, bokmal, bulgarian, catalan, coptic, 
croatian, czech, danish, dutch, esperanto, estonian, farsi, finnish, french, ga
lician, german, german-x-2009-06-19, greek, gujarati, hindi, hungarian, iceland
ic, indonesian, interlingua, irish, italian, kannada, kurmanji, lao, latin, lat
vian, lithuanian, malayalam, marathi, mongolian, mongolianlmc, monogreek, ngerm
an, ngerman-x-2009-06-19, nynorsk, oriya, panjabi, pinyin, polish, portuguese, 
romanian, russian, sanskrit, serbian, slovak, slovenian, spanish, swedish, swis
sgerman, tamil, telugu, turkish, turkmen, ukenglish, ukrainian, uppersorbian, u
senglishmax, welsh, loaded.
("C:\Program Files\MiKTeX 2.9\tex\latex\base\report.cls"
Document Class: report 2007/10/19 v1.4h Standard LaTeX document class
("C:\Program Files\MiKTeX 2.9\tex\latex\base\size12.clo"))
("C:\Program Files\MiKTeX 2.9\tex\latex\graphics\graphicx.sty"
("C:\Program Files\MiKTeX 2.9\tex\latex\graphics\keyval.sty")
("C:\Program Files\MiKTeX 2.9\tex\latex\graphics\graphics.sty"
("C:\Program Files\MiKTeX 2.9\tex\latex\graphics\trig.sty")
("C:\Program Files\MiKTeX 2.9\tex\latex\00miktex\graphics.cfg")
("C:\Program Files\MiKTeX 2.9\tex\latex\pdftex-def\pdftex.def"
("C:\Program Files\MiKTeX 2.9\tex\generic\oberdiek\infwarerr.sty")
("C:\Program Files\MiKTeX 2.9\tex\generic\oberdiek\ltxcmds.sty"))))
("C:\Program Files\MiKTeX 2.9\tex\latex\ams\math\amsmath.sty"
For additional information on amsmath, use the `?' option.
("C:\Program Files\MiKTeX 2.9\tex\latex\ams\math\amstext.sty"
("C:\Program Files\MiKTeX 2.9\tex\latex\ams\math\amsgen.sty"))
("C:\Program Files\MiKTeX 2.9\tex\latex\ams\math\amsbsy.sty")
("C:\Program Files\MiKTeX 2.9\tex\latex\ams\math\amsopn.sty"))
(E:\notes\test.aux)
======================================================================
pdflatex.EXE: Cannot start MiKTeX package manager.
pdflatex.EXE: Data: Invalid syntax

======================================================================
 (E:\notes\title.tex
<./images/logo.png, id=1, 143.53625pt x 59.22125pt> <use ./images/logo.png>
[1{C:/ProgramData/MiKTeX/2.9/pdftex/config/pdftex.map} <E:/notes/images/logo.pn
g>])
Chapter 1.
<./images/1.jpg, id=12, 401.5pt x 301.125pt> <use ./images/1.jpg>
<./images/2.jpg, id=13, 401.5pt x 303.1325pt> <use ./images/2.jpg>
<./images/3.jpg, id=14, 401.5pt x 301.125pt> <use ./images/3.jpg>
<./images/4.jpg, id=15, 201.75375pt x 225.09094pt> <use ./images/4.jpg>
Overfull \hbox (2.61108pt too wide) in paragraph at lines 8--12
[] []

Overfull \hbox (2.61108pt too wide) in paragraph at lines 8--12
[] []
[1 <E:/notes/images/1.jpg> <E:/notes/images/2.jpg> <E:/notes/images/3.jpg> <E:/
notes/images/4.jpg>] <./images/6.png, id=19, 208.52907pt x 125.71968pt>
<use ./images/6.png>
Underfull \hbox (badness 10000) in paragraph at lines 18--23


Underfull \hbox (badness 10000) in paragraph at lines 18--23


Underfull \hbox (badness 10000) in paragraph at lines 24--31


Underfull \hbox (badness 10000) in paragraph at lines 24--31


Underfull \hbox (badness 10000) in paragraph at lines 24--31

[2 <E:/notes/images/6.png (PNG copy)>]

Package amsmath Warning: Foreign command \over;
(amsmath)                \frac or \genfrac should be used instead
(amsmath)                 on input line 38.


Underfull \hbox (badness 10000) in paragraph at lines 43--46


Underfull \hbox (badness 10000) in paragraph at lines 50--51

! Missing } inserted.
<inserted text> 
                }
l.59 \end{flalign*}
                   
?

 

[yenchin]

To use the \boxed{} command, I think you need to load amsmath package.

 

[D H]

To use the \boxed{} command, I think you need to load amsmath package.

snshusat161 is doing just that. Look at the LaTeX output:

("C:\Program Files\MiKTeX 2.9\tex\latex\ams\math\amsmath.sty"
For additional information on amsmath, use the `?' option.

Not working

and after using \boxed in E_1 & = 4.44 N_1.B_m.A.f

I get the following error:[error output elided]

Well of course it's not working. You can't box around the separator character "&". That doesn't make sense.

What you can do is to put a box around the right hand side of your final equation:

\begin{align*}
E_1 & = \frac{e_{1max}}{\sqrt{2}}\\
& = \frac{N_1.{\phi}_m.w}{\sqrt{2}}\\
& = \frac{N_1{\phi}_m.2\pi.f}{\sqrt{2}}\\
\\
E_1 & = 4.44 N_1.{\phi}_m.f \\
\\
E_1 &= \boxed{4.44 N_1.B_m.A.f}
\end{align*}

$$\begin{align} E_1 & = \frac{e_{1max}}{\sqrt{2}}\\ & = \frac{N_1.{\phi}_m.w}{\sqrt{2}}\\ & = \frac{N_1{\phi}_m.2\pi.f}{\sqrt{2}}\\ \\ E_1 & = 4.44 N_1.{\phi}_m.f \\ \\ E_1 &= \boxed{4.44 N_1.B_m.A.f} \end{align}$$You can box the entire final equation as well, but you'll have to make your final equation standalone:

\begin{align*}
E_1 & = \frac{e_{1max}}{\sqrt{2}}\\
& = \frac{N_1.{\phi}_m.w}{\sqrt{2}}\\
& = \frac{N_1{\phi}_m.2\pi.f}{\sqrt{2}}\\
\\
E_1 & = 4.44 N_1.{\phi}_m.f
\end{align*}
\begin{equation*}
\boxed{E_1 = 4.44 N_1.B_m.A.f}
\end{equation*}

$$\begin{align} E_1 & = \frac{e_{1max}}{\sqrt{2}}\\ & = \frac{N_1.{\phi}_m.w}{\sqrt{2}}\\ & = \frac{N_1{\phi}_m.2\pi.f}{\sqrt{2}}\\ \\ E_1 & = 4.44 N_1.{\phi}_m.f \end{align}$$$$\boxed{E_1 = 4.44 N_1.B_m.A.f}$$
BTW, it would have been helpful in the original post if you had specified that you wanted to do this in a flalign environment.

 

[snshusat161]

Thanks D H. You are great! :)

 

[robphy]

$$\begin{align*} E_1 & = \frac{e_{1max}}{\sqrt{2}}\\ & = \frac{N_1.{\phi}_m.w}{\sqrt{2}}\\ & = \frac{N_1{\phi}_m.2\pi.f}{\sqrt{2}}\\ \\ E_1 & = 4.44 N_1.{\phi}_m.f \\ \\ E_1 &= \fbox{4.44 N_1.B_m.A.f} \end{align*}$$
\fbox works in ordinary $\LaTeX$... but you'll need to use \fbox{$math expression$}