# [LaTeX] Using Matrix

\documentclass{article}
\usepackage{amsmath}
\begin{document}
$\begin{bmatrix} x_{11} & x_{12} & x_{13} & \dots & x_{1n} \\ x_{21} & x_{22} & x_{23} & \dots & x_{2n} \\ \hdotsfor{5} \\ x_{d1} & x_{d2} & x_{d3} & \dots & x_{dn} \end{bmatrix} = \begin{bmatrix} x_{11} & x_{12} & x_{13} & \dots & x_{1n} \\ x_{21} & x_{22} & x_{23} & \dots & x_{2n} \\ \vdots & \vdots & \vdots & \ddots & \vdots \\ x_{d1} & x_{d2} & x_{d3} & \dots & x_{dn} \end{bmatrix}$
\end{document}

#### Reference

https://tex.stackexchange.com/questions/204621/matrix-in-latex

# [C/C++] Finding trailing 0s in a binary number

int bitcount(unsigned __int64 value)
{
if (!value)
return SOME_DEFAULT_VALUE;

value &= -value;
unsigned int lsb = (unsigned) value | (unsigned) (value >> 32);
return (int)(((((((((((unsigned) (value >> 32) != 0) * 2)
+ ((lsb & 0xffff0000) != 0)) * 2)
+ ((lsb & 0xff00ff00) != 0)) * 2)
+ ((lsb & 0xf0f0f0f0) != 0)) * 2)
+ ((lsb & 0xcccccccc) != 0)) * 2)
+ ((lsb & 0xaaaaaaaa) != 0);
}
int bitcount(unsigned char x)
{
int b;
for(b=0; b<7 && !(x&1); x>>=1) b++;

return b;
}

#### Reference

https://stackoverflow.com/questions/7812044/finding-trailing-0s-in-a-binary-number

# [C/C++] Dynamically allocating 2D array in C

main: malloc.c:2405: sysmalloc: Assertion (old_top == initial_top (av) && old_size == 0) || ((unsigned long) (old_size) >= MINSIZE && prev_inuse (old_top) && ((unsigned long) old_end & (pagesize – 1)) == 0)’ failed.
This most likely means that there is a mistake regarding usage of “sizeof”

#### Reference

Various methods to allocate 2D array: https://www.geeksforgeeks.org/dynamically-allocate-2d-array-c/
Common mistake: https://stackoverflow.com/questions/46803671/sysmalloc-assertion

# [Python] Remove runtime warnings

import warnings
warnings.filterwarnings('ignore', category=RuntimeWarning)
`