🌐 AI搜索 & 代理 主页
Skip to content

Commit eea90be

Browse files
committed
PR review comments
1 parent 604868a commit eea90be

File tree

2 files changed

+10
-5
lines changed

2 files changed

+10
-5
lines changed

scripts/install-mkdocs.sh

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -9,4 +9,4 @@ pip install \
99
mkdocs-git-revision-date-localized-plugin \
1010
mkdocs-simple-hooks \
1111
mkdocs-rss-plugin \
12-
mkdocs-git-committers-plugin-2
12+
plugins/mkdocs-git-committers-plugin-2

src/others/pells_equation.md

Lines changed: 9 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -22,16 +22,21 @@ This factorization is important because it shows the connection to quadratic irr
2222

2323
The norm of an expression $u + v \sqrt{d}$ is defined as $N(u + v \sqrt{d}) = (u + v \sqrt{d})(u - v \sqrt{d}) = u^2 - d v^2$. The norm is multiplicative: $N(ab) = N(a)N(b)$. This property is crucial in the descent argument below.
2424

25-
We will prove that all solutions to Pell's equation are given by powers of the smallest positive solution. Let's assume it to be $x_0 + y_0 \sqrt{d}$, where $x_0 > 1$ is the smallest possible value for $x$.
25+
We will prove that all solutions to Pell's equation are given by powers of the smallest non-trivial solution. Let's assume it to be the minimum possible $x_0 + y_0 \sqrt{d} > 1$. For such a solution, it also holds that $y_0 > 0$, and its $x_0 > 1$ is the smallest possible value for $x$.
2626

2727
## Method of Descent
2828
Suppose there is a solution $u + v \cdot \sqrt{d}$ such that $u^{2} - d \cdot v^{2} = 1$ and is not a power of $( x_{0} + \sqrt{d} \cdot y_{0} )$
2929
Then it must lie between two powers of $( x_{0} + \sqrt{d} \cdot y_{0} )$.
30-
i.e, For some n, $( x_{0} + \sqrt{d} \cdot y_{0} )^{n} < u + v \cdot \sqrt{d} < ( x_{0} + \sqrt{d} \cdot y_{0} )^{n+1}$
30+
i.e, For some $n$,
31+
$$
32+
( x_{0} + \sqrt{d} \cdot y_{0} )^{n} < u + v \cdot \sqrt{d} < ( x_{0} + \sqrt{d} \cdot y_{0} )^{n+1}
33+
$$
3134

32-
Multiplying the above inequality by $( x_{0} - \sqrt{d} \cdot y_{0} )^{n}$,(which is > 0 and < 1) we get
35+
Multiplying the above inequality by $( x_{0} - \sqrt{d} \cdot y_{0} )^{n}$,(which is $> 0$ and $< 1$) we get
3336

34-
$1 < (u + v \cdot \sqrt{d})( x_{0} - \sqrt{d} \cdot y_{0} )^{n} < ( x_{0} + \sqrt{d} \cdot y_{0} )$
37+
$$
38+
1 < (u + v \cdot \sqrt{d})( x_{0} - \sqrt{d} \cdot y_{0} )^{n} < ( x_{0} + \sqrt{d} \cdot y_{0} )
39+
$$
3540
Because both $(u + v \cdot \sqrt{d})$ and $( x_{0} - \sqrt{d} \cdot y_{0} )^{n}$ have norm 1, their product is also a solution.
3641
But this contradicts our assumption that $( x_{0} + \sqrt{d} \cdot y_{0} )$ is the smallest solution. Therefore, there is no solution between $( x_{0} + \sqrt{d} \cdot y_{0} )^{n}$ and $( x_{0} + \sqrt{d} \cdot y_{0} )^{n+1}$.
3742

0 commit comments

Comments
 (0)