Useful links:

two physics forums:
http://www.physicsforums.com/
—-Introducing LaTeX Math Typesetting
http://www.advancedphysics.org/

two / web service sites:
http://www.codecogs.com/components/equationeditor/equationeditor.php?lang=en-en
http://www.mathtran.org/

a group blog of several well-known scientists:
http://cosmicvariance.com/

& test












test:

tex:a^2+b^2=c^2
tex:1 + 1/2 + 1/4 + \ldots + 1/2^n
tex:\displaystyle{\sum_0^\infty x^n/n!}
tex:\displaystyle{\sum_0^\infty (-1)^nx^n/n!}
tex:\displaystyle{\sum_0^\infty x^n/n}
tex:\displaystyle{\sum_0^n 2^{-n}}
tex:\displaystyle{\delta I = \int_\textit{A}^\textit{B}{\left( \frac{ \partial{L} }{ \partial {q} } - \frac{d}{dq} \frac{ \partial{L} }{ \partial \dot{q} } \right)\delta q dt}}

tex:\displaystyle{\frac{1}{2}}
tex:R^a{}_{bcd}
tex:\nabla \times C
tex:\mathbb{RC}
tex:\lambda_j = \vec{\lambda} \cdot \vec{e}_j
tex:\lambda_j = \mathbf{\lambda} \cdot \mathbf{e}_j
tex:\displaystyle{v(t) = v_0 + \frac{1}{2} a t^2}
tex:\displaystyle{\gamma \equiv \frac{1}{\sqrt{1 - v^2/c^2}}}
tex:\displaystyle{\ddot{x} = \frac {d^2x} {dt^2}}

tex:\displaystyle{f’(x) = \lim_{h \to 0} \left( \frac{f(x+h)-f(x)}{h} \right)}
tex:\displaystyle{x = \frac{-b \pm \sqrt{b^2 – 4ac}}{2a}}

tex:ab\;|\;a b\;|\;a\! b\;|\;a\: b\;|\;a\, b\;|\;a\; b

tex:\displaystyle{e^x = \sum_{n=0}^\infty \frac{x^n}{n!} = \lim_{n\rightarrow\infty} (1+x/n)^n}
tex:\displaystyle{\int_{0}^{1} x dx = \left[ \frac{1}{2}x^2 \right]_{0}^{1} = \frac{1}{2}}
tex:\displaystyle{L = \int_a^b \left( g_{\it ij} \dot u^i \dot u^j \right)^{1/2} dt}
tex:\iiint f(x,y,z)\,dx\,dy\,dz
tex:\lim_{\substack{x\rightarrow 0\\y\rightarrow 0}} f(x,y)
tex:\displaystyle{\int\dots\int_\textrm{paths} \exp{(iS(x,\dot{x})/\hbar)}\, \mathcal{D}x}
tex:A \alpha B \beta \Gamma \gamma \Delta \delta \dots \Phi \phi X \chi \Psi \psi \Omega \omega
tex:\displaystyle{\Gamma^l_{ki} = \frac{1}{2} g^{lj} (\partial_k g_{ij} + \partial_i g_{jk} - \partial_j g_{ki})}

tex:\displaystyle{i \hbar \frac{\partial \Psi}{\partial t} = - \frac{\hbar^2}{2 m} \ \frac{\partial^2{\Psi}}{{\partial x}^2} + V \Psi}
tex:\displaystyle{<\!\!{\phi|\psi}\!\!>\equiv \int \phi^*(x) \psi(x)\,dx}

tex:R^a{}_{bcd}
tex:x_i^2
tex:{x_i}^2

tex:e^+e^-\rightarrow u \bar{u}
tex:e^+e^-\rightarrow \mu^+\mu^-
tex:e^+e^-\rightarrow \gamma\gamma
tex:\displaystyle{\int_{0}^{1} \frac{2x}{\sqrt{a^2 + x^2}} dx = \left[ \sqrt{a^2 + x^2} \right]_{0}^{1}}

The LaTeX expression: “\sqrt(3){ 1 + x^2 }” will not work correctly with tex:\TeX: tex:\sqrt(3){ 1 + x^2 }, use “\root 3 \of { 1 + x^2 }” instead: tex:\root 3 \of { 1 + x^2 }.

The LaTeX expression: “\matrix {a & b \cr c & d }” will not work correctly with tex:\TeX: tex:\matrix {a & b \cr c & d }, use “\left[ \matrix {a & b \cr c & d} \right]” instead: tex:\left[ \matrix {a & b \cr c & d} \right].
tex:\overbrace{a+b+\cdots+z}
tex:\TeX