Table of Contents

1 Remarkable

2 Android

H2O APN setting

  • Name: ATT Nextgenphone
  • APN: att.mvno
  • Port: 80
  • MMSC: http://mmsc.mobile.att.net
  • MMS Proxy:
  • MMS Port: 80
  • MCC: 310
  • MNC: 410
  • APN Type: default, mms, supl, fota, hipri
  • APN Protocol: IPv4/IPv6

Unset but with value:

  • MVNO Type: None
  • Bearer: Unspecified

Everything else Not set, including

  • Proxy
  • Username
  • Password
  • Server
  • Authentication Type
  • MVNO Value

3 C

3.1 Context Sensitivity of C

Here is the C lexer rule and grammar for yacc

4 Math

4.1 Calculus

Calculus has two main branches:

  • differential calculus
    • it is mainly about derivative. The process of finding a derivative is called differentiation.
    • \(\frac{dy}{dx}|_{a}\) is Leibniz's notation
    • f'(a) is Lagrange's notation
  • integral calculus
    • definite integral
    • indefinite integral (also antiderivative)

4.2 Lagrange multiplier

When solving a maxima of a function, with subject to a constraint, we often use Lagrange multiplier. Say:

  • maximize \(f(x,y)\)
  • subject to \(g(x,y)=0\)

We are going to introduce the Lagrange multiplier \(\lambda\) such that

  • \(L(x,y,\lambda) = f(x,y) - \lambda g(x,y)\) is called Lagrange function.
  • Compute the gradient of L, and compute the stationary points. Those points will be the space of the solution to the original maxima problem.

The intuition: at a maximum, f(x,y) cannot be increasing in the direction of any neighboring point where g = 0.