Manual: The Kronecker symbol - libzahl - big integer library | |
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commit 019da3a9e7f81cd882d0383ac707ce098013b4a9 | |
parent 60dd5110e21d1aedc047f2033af74330df552e40 | |
Author: Mattias Andrée <[email protected]> | |
Date: Mon, 25 Jul 2016 16:38:43 +0200 | |
Manual: The Kronecker symbol | |
Signed-off-by: Mattias Andrée <[email protected]> | |
Diffstat: | |
M doc/not-implemented.tex | 60 +++++++++++++++++++++++++++++… | |
1 file changed, 56 insertions(+), 4 deletions(-) | |
--- | |
diff --git a/doc/not-implemented.tex b/doc/not-implemented.tex | |
@@ -163,7 +163,8 @@ so a compressed lookup table can be used for small $p$. | |
\left ( \frac{a}{n} \right ) = | |
\prod_k \left ( \frac{a}{p_k} \right )^{n_k}, | |
}\) | |
-where $n$ = $\displaystyle{\prod_k p_k^{n_k}}$, and $p_k \in \textbf{P}$. | |
+where $\displaystyle{n = \prod_k p_k^{n_k} > 0}$, | |
+and $p_k \in \textbf{P}$. | |
\vspace{1em} | |
Like the Legendre symbol, the Jacobi symbol is $n$-period over $a$. | |
@@ -197,14 +198,65 @@ Use the following algorithm to calculate the Jacobi symbo… | |
\STATE \textbf{start over} | |
\end{algorithmic} | |
\end{minipage} | |
-\vspace{1em} | |
- | |
\subsection{Kronecker symbol} | |
\label{sec:Kronecker symbol} | |
-TODO | |
+The Kronecker symbol | |
+$\displaystyle{\left ( \frac{a}{n} \right )}$ | |
+is a generalisation of the Jacobi symbol, | |
+where $n$ can be any integer. For positive | |
+odd $n$, the Kronecker symbol is equal to | |
+the Jacobi symbol. For even $n$, the | |
+Kronecker symbol is $2n$-periodic over $a$, | |
+the Kronecker symbol is zero for all | |
+$(a, n)$ with both $a$ and $n$ are even. | |
+ | |
+\vspace{1em} | |
+\noindent | |
+\( \displaystyle{ | |
+ \left ( \frac{a}{2^k \cdot n} \right ) = | |
+ \left ( \frac{a}{n} \right ) \cdot \left ( \frac{a}{2} \right )^k, | |
+}\) | |
+where | |
+\( \displaystyle{ | |
+ \left ( \frac{a}{2} \right ) = | |
+ \left \lbrace \begin{array}{rl} | |
+ 1 & \text{if}~ a \equiv 1, 7 ~(\text{Mod}~ 8) \\ | |
+ -1 & \text{if}~ a \equiv 3, 5 ~(\text{Mod}~ 8) \\ | |
+ 0 & \text{otherwise} | |
+ \end{array} \right . | |
+}\) | |
+ | |
+\vspace{1em} | |
+\noindent | |
+\( \displaystyle{ | |
+ \left ( \frac{-a}{n} \right ) = | |
+ \left ( \frac{a}{n} \right ) \cdot \left ( \frac{a}{-1} \right ), | |
+}\) | |
+where | |
+\( \displaystyle{ | |
+ \left ( \frac{a}{-1} \right ) = | |
+ \left \lbrace \begin{array}{rl} | |
+ 1 & \text{if}~ a \ge 0 \\ | |
+ -1 & \text{if}~ a < 0 | |
+ \end{array} \right . | |
+}\) | |
+\vspace{1em} | |
+ | |
+\noindent | |
+However, for $n = 0$, the symbol is defined as | |
+ | |
+\vspace{1em} | |
+\noindent | |
+\( \displaystyle{ | |
+ \left ( \frac{a}{0} \right ) = | |
+ \left \lbrace \begin{array}{rl} | |
+ 1 & \text{if}~ a = \pm 1 \\ | |
+ 0 & \text{otherwise.} | |
+ \end{array} \right . | |
+}\) | |
\subsection{Power residue symbol} |