Quick Calculation 3.6

A First Course in String Theory

.

Verify that for \displaystyle{d=3} equation (3.74) coincides with (3.67).

~~~

Eq. (3.67):

\displaystyle{E(r) = \frac{q}{4 \pi r^2}}

Eq. (3.74):

\displaystyle{E(r) = \frac{\Gamma\left( \frac{d}{2} \right)}{2 \pi^{\frac{d}{2}}} \frac{q}{r^{d-1}}}

.

When \displaystyle{d=3},

\displaystyle{\begin{aligned}    E(r)   &= \frac{\Gamma\left( \frac{3}{2} \right)}{2 \pi^{\frac{3}{2}}} \frac{q}{r^{2}} \\ \\    &= \frac{\sqrt{\pi}}{2} \frac{1}{2 \pi \pi^{\frac{1}{2}}} \frac{q}{r^{2}} \\ \\     &= \frac{1}{4 \pi} \frac{q}{r^{2}} \\ \\     \end{aligned}  }

— Me@2022-05-30 01:15:00 PM

.

.

2022.05.30 Monday (c) All rights reserved by ACHK

Emulator

If a flight-simulator could transport you from A to B then it would be a flight-emulator.

An emulator can replace the original for real use.

A Virtual PC emulates a PC.

A simulator is a model for study and analysis.

An emulator will always have to operate close to real-time. For a simulator that is not always the case. A geological simulation could do 1000 years/second or more.

— edited Dec 26, 2018 at 17:37

— answered Oct 18, 2009 at 11:25

— Henk Holterman

.

Virtual PC does not emulate, it virtualizes. QEmu, on the other hand, does emulate. In both cases, the name should be a hint. – Jörg W Mittag Oct 18, 2009 at 12:36

— Stack Overflow

.

.

2022.05.29 Sunday ACHK