\[f(x) = \int_{-\infty}^\infty \hat f(\xi)\,e^{2 \pi i \xi x} \,d\xi\]

📝 enable katex with front matter in current page:

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math: katex
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  1. math block:

    \(K(a,b) = \int \mathcal{D}x(t) \exp(2\pi i S[x]/\hbar)\)

     $$
 K(a,b) = \int \mathcal{D}x(t) \exp(2\pi i S[x]/\hbar)
 $$

  2. math inline:

    this is inline function $f(x) = \int_{-\infty}^\infty \hat f(\xi)\,e^{2 \pi i \xi x} \,d\xi$ and another inline function $ e = m c^2 $

     this is inline function $f(x) = \int_{-\infty}^\infty \hat f(\xi)\,e^{2 \pi i \xi x} \,d\xi$ and another inline function $ e = m c^2 $

  3. some usages;

    inline is displayed: \(f(x) = \int_{-\infty}^\infty \hat f(\xi)\,e^{2 \pi i \xi x} \,d\xi\)

    \(f(x) = \int_{-\infty}^\infty \hat f(\xi)\,e^{2 \pi i \xi x} \,d\xi\)

    inline is displayed: $$f(x) = \int_{-\infty}^\infty \hat f(\xi)\,e^{2 \pi i \xi x} \,d\xi$$

center is displayed:

$$f(x) = \int_{-\infty}^\infty \hat f(\xi)\,e^{2 \pi i \xi x} \,d\xi$$

  4. other equations for test:

    \[y=\frac{1}{2} \times \sqrt{x^2-1} \\ y=\cfrac{1}{2+\cfrac{1}{2}} \\ y=\int \! (x^2-1) dx \\ y=\int (x^2-1) dx \\ y=\int_{a}^{b=10} (x^2-1) dx \\ y=\sum_{x=1}^ {100} (x^2-1)- 1 \\ BER= erfc(\frac{Q}{\sqrt{2}})\] \[\fbox {this is a demo equation: } \\ BER= erfc(\frac{Q}{\sqrt{2}})\] 
     $$
 y=\frac{1}{2} \times \sqrt{x^2-1} \\
 y=\cfrac{1}{2+\cfrac{1}{2}}     \\
 y=\int \! (x^2-1) dx             \\
 y=\int (x^2-1) dx                \\
 y=\int_{a}^{b=10} (x^2-1) dx            \\
 y=\sum_{x=1}^ {100} (x^2-1)- 1          \\
 BER= erfc(\frac{Q}{\sqrt{2}})
 $$
    
 $$
 \fbox {this is a demo equation: }   \\
 BER= erfc(\frac{Q}{\sqrt{2}})
 $$