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| author | Juan Marín Noguera <juan@mnpi.eu> | 2025-05-16 22:18:44 +0200 |
|---|---|---|
| committer | Juan Marín Noguera <juan@mnpi.eu> | 2025-05-16 22:18:44 +0200 |
| commit | 4f670b750af5c11e1eac16d9cd8556455f89f46a (patch) | |
| tree | e0f8d7b33df2727d89150f799ee8628821fda80a /3.3.3.lyx | |
| parent | 16ccda6c459c0fd7ca2081e9d541124c28b0c556 (diff) | |
Changed layout for more manageable volumes
Diffstat (limited to '3.3.3.lyx')
| -rw-r--r-- | 3.3.3.lyx | 1383 |
1 files changed, 0 insertions, 1383 deletions
diff --git a/3.3.3.lyx b/3.3.3.lyx deleted file mode 100644 index d03c773..0000000 --- a/3.3.3.lyx +++ /dev/null @@ -1,1383 +0,0 @@ -#LyX 2.4 created this file. For more info see https://www.lyx.org/ -\lyxformat 620 -\begin_document -\begin_header -\save_transient_properties true -\origin unavailable -\textclass book -\begin_preamble -\input defs -\end_preamble -\use_default_options true -\maintain_unincluded_children no -\language english -\language_package default -\inputencoding utf8 -\fontencoding auto -\font_roman "default" "default" -\font_sans "default" "default" -\font_typewriter "default" "default" -\font_math "auto" "auto" -\font_default_family default -\use_non_tex_fonts false -\font_sc false -\font_roman_osf false -\font_sans_osf false -\font_typewriter_osf false -\font_sf_scale 100 100 -\font_tt_scale 100 100 -\use_microtype false -\use_dash_ligatures true -\graphics default -\default_output_format default -\output_sync 0 -\bibtex_command default -\index_command default -\float_placement class -\float_alignment class -\paperfontsize default -\spacing single -\use_hyperref false -\papersize default -\use_geometry false -\use_package amsmath 1 -\use_package amssymb 1 -\use_package cancel 1 -\use_package esint 1 -\use_package mathdots 1 -\use_package mathtools 1 -\use_package mhchem 1 -\use_package stackrel 1 -\use_package stmaryrd 1 -\use_package undertilde 1 -\cite_engine basic -\cite_engine_type default -\biblio_style plain -\use_bibtopic false -\use_indices false -\paperorientation portrait -\suppress_date false -\justification true -\use_refstyle 1 -\use_formatted_ref 0 -\use_minted 0 -\use_lineno 0 -\index Index -\shortcut idx -\color #008000 -\end_index -\secnumdepth 3 -\tocdepth 3 -\paragraph_separation indent -\paragraph_indentation default -\is_math_indent 0 -\math_numbering_side default -\quotes_style english -\dynamic_quotes 0 -\papercolumns 1 -\papersides 1 -\paperpagestyle default -\tablestyle default -\tracking_changes false -\output_changes false -\change_bars false -\postpone_fragile_content false -\html_math_output 0 -\html_css_as_file 0 -\html_be_strict false -\docbook_table_output 0 -\docbook_mathml_prefix 1 -\end_header - -\begin_body - -\begin_layout Subsubsection -First Set -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -exerc1[M10] -\end_layout - -\end_inset - -Express -\begin_inset Formula $x\bmod y$ -\end_inset - - in terms of the sawtooth and -\begin_inset Formula $\delta$ -\end_inset - - functions. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -We have -\begin_inset Formula $((x))-\frac{1}{2}\delta(x)=x-\lfloor x\rfloor-\frac{1}{2}$ -\end_inset - -, - so -\begin_inset Formula $\lfloor x\rfloor=x-((x))+\tfrac{1}{2}(\delta(x)-1)$ -\end_inset - -. - Therefore -\begin_inset Formula -\begin{multline*} -x\bmod y=x-y\left\lfloor \frac{x}{y}\right\rfloor =x-y\left(\frac{x}{y}-\left(\left(\frac{x}{y}\right)\right)+\frac{1}{2}\left(\delta(\tfrac{x}{y})-1\right)\right)=\\ -=\left(\left(\left(\frac{x}{y}\right)\right)+\frac{1-\delta(\frac{x}{y})}{2}\right)y. -\end{multline*} - -\end_inset - - -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc4[M19] -\end_layout - -\end_inset - -If -\begin_inset Formula $m=10^{10}$ -\end_inset - -, - what is the highest possible value of -\begin_inset Formula $d$ -\end_inset - - (in the notation of Theorem P), - given that the potency of the generator is 10? -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -It's -\begin_inset Formula $d=2\cdot5^{10}$ -\end_inset - -. - First, - we note that -\begin_inset Formula -\[ -(2\cdot5^{10})^{9}\bmod10^{10}=2^{9}5^{90}\bmod2^{10}5^{10}=2^{9}5^{10}(5^{80}\bmod2)=m/2\neq0, -\] - -\end_inset - - and that -\begin_inset Formula $(2\cdot5^{10})^{10}\bmod10^{10}=2^{10}5^{100}\bmod2^{10}5^{10}=0$ -\end_inset - -, - so if -\begin_inset Formula $b=d$ -\end_inset - - we have potency 10. - Second, - we note that, - since -\begin_inset Formula $d\mid m$ -\end_inset - -, - and any divisor of -\begin_inset Formula $m$ -\end_inset - - greater that -\begin_inset Formula $2\cdot5^{10}$ -\end_inset - - has to be a multiple at least of -\begin_inset Formula $2^{2}$ -\end_inset - - and of -\begin_inset Formula $5^{2}$ -\end_inset - -, - and therefore of 100, - then -\begin_inset Formula $b$ -\end_inset - - would have to be a multiple of 100 and the potency would be at most 5. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc7[M24] -\end_layout - -\end_inset - -Give a proof of the reciprocity law (19), - when -\begin_inset Formula $c=0$ -\end_inset - -, - by using the general reciprocity law of exercise 1.2.4–45. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - - -\begin_inset Note Greyedout -status open - -\begin_layout Plain Layout -(I had to look up the solution, - obviously.) -\end_layout - -\end_inset - -In this case, - the law reduces to -\begin_inset Formula -\begin{multline*} -\sigma(h,k,0)+\sigma(k,h,0)=\\ -=12\sum_{0\leq j<k}\left(\left(\frac{j}{k}\right)\right)\left(\left(\frac{hj}{k}\right)\right)+12\sum_{0\leq j<h}\left(\left(\frac{j}{h}\right)\right)\left(\left(\frac{kj}{h}\right)\right)=\frac{h}{k}+\frac{k}{h}+\frac{1}{hk}-3. -\end{multline*} - -\end_inset - -where -\begin_inset Formula $0<h\leq k$ -\end_inset - - are coprime integers. - The last equation from exercise 1.2.4–45 with -\begin_inset Formula $k=2$ -\end_inset - - tells us that -\begin_inset Formula -\[ -\sum_{1\leq j<n}\left\lfloor \frac{mj}{n}\right\rfloor \left(\left\lfloor \frac{mj}{n}\right\rfloor +1\right)+2\sum_{1\leq j<m}j\left\lceil \frac{jn}{m}\right\rceil =nm(m-1) -\] - -\end_inset - -for -\begin_inset Formula $m,n\in\mathbb{N}$ -\end_inset - -, - where we multiply by 2 and then set the lower bound of the sums to 1 because terms with -\begin_inset Formula $j=0$ -\end_inset - - evaluate to 0. - Now, - since -\begin_inset Formula $h$ -\end_inset - - and -\begin_inset Formula $k$ -\end_inset - - are coprime, - for -\begin_inset Formula $j\in\{1,\dots,k-1\}$ -\end_inset - -, -\begin_inset Formula -\begin{align*} -\left(\left(\frac{hj}{k}\right)\right) & =\frac{hj}{k}-\left\lfloor \frac{hj}{k}\right\rfloor -\frac{1}{2}=\frac{hj}{k}-\left\lceil \frac{hj}{k}\right\rceil +\frac{1}{2}, -\end{align*} - -\end_inset - -so substituting above, -\begin_inset Formula -\begin{multline*} -S\coloneqq kh(h-1)=\\ -=\sum_{j=1}^{k-1}\left(\frac{hj}{k}-\left(\left(\frac{hj}{k}\right)\right)-\frac{1}{2}\right)\left(\frac{hj}{k}-\left(\left(\frac{hj}{k}\right)\right)+\frac{1}{2}\right)+\\ -+2\sum_{j=1}^{h-1}j\left(\frac{kj}{h}-\left(\left(\frac{kj}{h}\right)\right)+\frac{1}{2}\right)=\\ -=\frac{h^{2}}{k^{2}}\sum_{j=1}^{k-1}j^{2}-\frac{2h}{k}\sum_{j=1}^{k-1}j\left(\left(\frac{hj}{k}\right)\right)+\sum_{j=1}^{k-1}\left(\left(\frac{hj}{k}\right)\right)^{2}-\frac{k-1}{4}+\frac{2k}{h}\sum_{j=1}^{h-1}j^{2}-\\ --2\sum_{j=1}^{h-1}j\left(\left(\frac{kj}{h}\right)\right)+\frac{h^{2}-h}{2}. -\end{multline*} - -\end_inset - -Now, -\begin_inset Formula -\begin{align*} -\sum_{j=1}^{k-1}\left(\left(\frac{hj}{k}\right)\right) & =\sum_{j=1}^{k-1}\left(\left(\frac{j}{k}\right)\right)=\sum_{j=1}^{k-1}\left(\frac{j}{k}-\frac{1}{2}\right)=\frac{k(k-1)}{2k}-\frac{k-1}{2}=0, -\end{align*} - -\end_inset - -so -\begin_inset Formula -\begin{multline*} -\sigma(h,k,0)=12\sum_{j=0}^{k-1}\left(\left(\frac{j}{k}\right)\right)\left(\left(\frac{hj}{k}\right)\right)=12\sum_{j=1}^{k-1}\left(\frac{j}{k}-\frac{1}{2}\right)\left(\left(\frac{hj}{k}\right)\right)=\\ -=12\sum_{j=1}^{k-1}\frac{j}{k}\left(\left(\frac{hj}{k}\right)\right). -\end{multline*} - -\end_inset - -In addition, -\begin_inset Formula -\[ -\sum_{j=1}^{k-1}j^{2}=\frac{(k-1)k(2k-1)}{6}=\frac{k}{6}(2k^{2}-3k+1)=\frac{k^{3}}{3}-\frac{k^{2}}{2}+\frac{k}{6}, -\] - -\end_inset - -and in particular -\begin_inset Formula -\begin{align*} -\sum_{j=1}^{k-1}\left(\left(\frac{hj}{k}\right)\right)^{2} & =\sum_{j=1}^{k-1}\left(\left(\frac{j}{k}\right)\right)^{2}\\ - & =\sum_{j=1}^{k-1}\frac{j^{2}}{k^{2}}-\sum_{j=1}^{k-1}\frac{j}{k}+\frac{k-1}{4}=\frac{k}{3}-\frac{1}{2}+\frac{1}{6k}-\frac{k-1}{2}+\frac{k-1}{4}\\ - & =\frac{k}{3}-\frac{1}{2}+\frac{1}{6k}-\frac{k-1}{4}, -\end{align*} - -\end_inset - -so finally -\begin_inset Formula -\begin{align*} -S= & \frac{kh^{2}}{3}-\frac{h^{2}}{2}+\frac{h^{2}}{6k}-\frac{h}{6}\sigma(h,k,0)+\frac{k}{3}-\frac{1}{2}+\frac{1}{6k}-\frac{k-1}{2}+\frac{2kh^{2}}{3}-kh+\\ - & +\frac{k}{3}-\frac{h}{6}\sigma(k,h,0)+\frac{h^{2}}{2}-\frac{h}{2}\\ -= & kh(h-1)-\frac{h}{2}+\frac{h^{2}}{6k}+\frac{k}{6}+\frac{1}{6k}-\frac{h}{6}\sigma(h,k,0)-\frac{h}{6}\sigma(k,h,0). -\end{align*} - -\end_inset - -With this, -\begin_inset Formula -\[ -\sigma(h,k,0)+\sigma(k,h,0)=-3+\frac{h}{k}+\frac{k}{h}+\frac{1}{hk}. -\] - -\end_inset - - -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc14[M20] -\end_layout - -\end_inset - -The linear congruential generator that has -\begin_inset Formula $m=2^{35}$ -\end_inset - -, - -\begin_inset Formula $a=2^{18}+1$ -\end_inset - -, - -\begin_inset Formula $c=1$ -\end_inset - -, - was given the serial correlation test on three batches of 1000 consecutive numbers, - and the result was a very high correlation, - between -\begin_inset Formula $0.2$ -\end_inset - - and -\begin_inset Formula $0.3$ -\end_inset - -, - in each case. - What is the serial correlation of this generator, - taken over all -\begin_inset Formula $2^{35}$ -\end_inset - - numbers of the period? -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -The generator has full period by 3.2.1.2–A, - and -\begin_inset Formula $x'\coloneqq2^{18}-1$ -\end_inset - - gives us -\begin_inset Formula $S(x')=0$ -\end_inset - -. - Thus, - by (17), - -\begin_inset Formula $C=(2^{35}\sigma(2^{18}+1,2^{35},1)-3+6(2^{35}-2^{18}))/(2^{70}-1)$ -\end_inset - -. - Now we calculate the Dedekind coefficient by Theorem D. -\begin_inset Formula -\begin{align*} -2^{35} & =(2^{17}-1)(2^{18}+1)+(2^{17}+1), & 1 & =0(2^{18}+1)+1;\\ -2^{18}+1 & =1(2^{17}+1)+2^{17}, & 1 & =0(2^{17}+1)+1;\\ -2^{17}+1 & =1\cdot2^{17}+1 & 1 & =0(2^{17})+1;\\ -2^{17} & =2^{17}\cdot1+0, & 1 & =1\cdot1+0. -\end{align*} - -\end_inset - -The number -\begin_inset Formula $h'\coloneqq2^{35}-2^{18}+1$ -\end_inset - - gives us -\begin_inset Formula $(2^{18}+1)h'\equiv1\pmod{2^{35}}$ -\end_inset - -, - so -\begin_inset Formula -\begin{multline*} -\sigma(2^{18}+1,2^{35},1)=\frac{(\cancel{2^{18}}+1)+(2^{35}\cancel{-2^{18}}+1)}{2^{35}}+\left((2^{17}-1)-6\cdot0+6\frac{1^{2}}{2^{35}(2^{18}+1)}\right)-\\ --\left(1-6\cdot0+\frac{6\cdot1^{2}}{(2^{18}+1)(2^{17}+1)}\right)+\left(1-6\cdot0+6\frac{1^{2}}{(2^{17}+1)2^{17}}\right)-\left(2^{17}-6\cdot1+6\frac{1^{2}}{2^{17}}\right)\\ -\\-3-2+1=\\ -=\cancel{1}+\frac{2}{2^{35}}\cancel{+2^{17}}\cancel{-1}+\frac{6}{2^{53}+2^{35}}\cancel{-1}-\frac{6}{2^{35}+2^{18}+2^{17}+1}\cancel{+1}+\frac{6}{2^{34}+2^{17}}\cancel{-2^{17}}+6-\frac{6}{2^{17}}-4=\\ -=2+\frac{1}{2^{34}}+6\left(\frac{1}{2^{53}+2^{35}}-\frac{1}{2^{35}+3\cdot2^{17}+1}+\frac{1}{2^{34}+2^{17}}-\frac{1}{2^{17}}\right)=\\ -=2+\frac{1}{2^{34}}+6\frac{2^{17}+1-2^{35}\cancel{+2^{36}+2^{18}}-2^{53}\cancel{-2^{36}}-2^{35}\cancel{-2^{18}}}{2^{35}(2^{18}+1)(2^{17}+1)}=\\ -=2+\frac{1}{2^{34}}+3\frac{(-2^{36}+1)\cancel{(2^{17}+1)}}{2^{34}(2^{18}+1)\cancel{(2^{17}+1)}}=2+\frac{1}{2^{34}}-3\frac{2^{18}-1}{2^{34}}=2-\frac{3\cdot2^{18}-4}{2^{34}}=\\ -=2-\frac{3\cdot2^{16}-1}{2^{32}}=\frac{2^{33}-2^{17}-2^{16}+1}{2^{32}}=\frac{(2^{17}-1)(2^{16}-1)}{2^{32}}. -\end{multline*} - -\end_inset - -Thus, -\begin_inset Formula -\begin{multline*} -C=\frac{8(2^{17}-1)(2^{16}-1)-3+6\cdot2^{18}(2^{17}-1)}{2^{70}-1}=\frac{91624920407}{393530540239137101141}\cong\\ -\cong2.33\cdot10^{-10}. -\end{multline*} - -\end_inset - - -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc18[M23] -\end_layout - -\end_inset - -(U. - Dieter.) Given positive integers -\begin_inset Formula $h$ -\end_inset - -, - -\begin_inset Formula $k$ -\end_inset - -, - -\begin_inset Formula $z$ -\end_inset - -, - let -\begin_inset Formula -\[ -S(h,k,c,z)=\sum_{0\leq j<z}\left(\left(\frac{hj+c}{k}\right)\right). -\] - -\end_inset - -Show that this sum can be evaluated in closed form, - in terms of the generalized Dedekind sums and the sawtooth function. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -Let -\begin_inset Formula $S_{j}\coloneqq\left(\left(\frac{hj+c}{k}\right)\right)$ -\end_inset - - and note that -\begin_inset Formula $S_{j}=S_{j+k}$ -\end_inset - - for all -\begin_inset Formula $j$ -\end_inset - -. - Thus, - if -\begin_inset Formula $z>k$ -\end_inset - -, -\begin_inset Formula -\[ -\sum_{0\leq j<z}\left(\left(\frac{hj+c}{k}\right)\right)=\left\lfloor \frac{z}{k}\right\rfloor \sum_{0\leq j<k}\left(\left(\frac{hj+c}{k}\right)\right)+\sum_{0\leq j<z\bmod k}\left(\left(\frac{hj+c}{k}\right)\right), -\] - -\end_inset - -so we may assume -\begin_inset Formula $z\leq k$ -\end_inset - - from now on. - Now, - -\begin_inset Formula $\left\lfloor \frac{j}{k}\right\rfloor -\left\lfloor \frac{j-z}{k}\right\rfloor $ -\end_inset - - is 1 when -\begin_inset Formula $0\leq j<z$ -\end_inset - - and 0 when -\begin_inset Formula $z\leq j<k$ -\end_inset - -, - so -\begin_inset Formula -\begin{multline*} -S(h,k,c,z)=\sum_{0\leq j<k}\left(\left\lfloor \frac{j}{k}\right\rfloor -\left\lfloor \frac{j-z}{k}\right\rfloor \right)\left(\left(\frac{hj+c}{k}\right)\right)=\\ -=\sum_{0\leq j<k}\left(\cancel{\frac{j}{k}}-\left(\left(\frac{j}{k}\right)\right)\cancel{-\frac{1}{2}}-\frac{\cancel{j}-z}{k}+\left(\left(\frac{j-z}{k}\right)\right)\cancel{+\frac{1}{2}}\right)\left(\left(\frac{hj+c}{k}\right)\right)+\\ -+\frac{1}{2}\left(\left(\frac{c}{k}\right)\right)-\frac{1}{2}\left(\left(\frac{hz+c}{k}\right)\right)=\\ -=\sum_{0\leq j<k}\left(\left(\left(\frac{j-z}{k}\right)\right)+\frac{z}{k}-\left(\left(\frac{j}{k}\right)\right)\right)\left(\left(\frac{hj+c}{k}\right)\right)+\frac{1}{2}\left(\left(\frac{c}{k}\right)\right)-\frac{1}{2}\left(\left(\frac{hz+c}{k}\right)\right). -\end{multline*} - -\end_inset - -Let's evaluate the sum term by term. - Clearly the term -\begin_inset Formula $-\left(\left(\frac{j}{k}\right)\right)$ -\end_inset - - sums to -\begin_inset Formula $-\frac{1}{12}\sigma(h,k,c)$ -\end_inset - -. - For the term with -\begin_inset Formula $\frac{z}{k}$ -\end_inset - -, - which is constant, - we use the argument used to derive Eq. - (13) in the text with -\begin_inset Formula $d\coloneqq\gcd\{h,k\}$ -\end_inset - -. - Finally, -\begin_inset Formula -\begin{multline*} -\sum_{0\leq j<k}\left(\left(\frac{j-z}{k}\right)\right)\left(\left(\frac{hj+c}{k}\right)\right)=\sum_{-z\leq j<k-z}\left(\left(\frac{j}{k}\right)\right)\left(\left(\frac{hj+c+hz}{k}\right)\right)=\\ -=\frac{1}{12}\sigma(h,k,c+hz). -\end{multline*} - -\end_inset - -Putting it all together, -\begin_inset Formula -\[ -S(h,k,c,z)=\frac{1}{12}\sigma(h,k,c+hz)-\frac{1}{12}\sigma(h,k,c)+\frac{zd}{k}\left(\left(\frac{c}{d}\right)\right)+\frac{1}{2}\left(\left(\frac{c}{k}\right)\right)-\frac{1}{2}\left(\left(\frac{hz+c}{k}\right)\right). -\] - -\end_inset - -For -\begin_inset Formula $z=k$ -\end_inset - -, - this simplifies to -\begin_inset Formula $d\left(\left(\frac{c}{d}\right)\right)$ -\end_inset - -, - and since -\begin_inset Formula $\left\lfloor \frac{z}{k}\right\rfloor +\frac{z\bmod k}{k}=\frac{z}{k}$ -\end_inset - -, - it's easy to check that this formula still applies when -\begin_inset Formula $z>k$ -\end_inset - -. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc19[M23] -\end_layout - -\end_inset - -Show that the -\emph on -serial test -\emph default - can be analyzed over the full period, - in terms of generalized Dedekind sums, - by finding a formula for the probability that -\begin_inset Formula $\alpha\leq X_{n}<\beta$ -\end_inset - - and -\begin_inset Formula $\alpha'\leq X_{n+1}<\beta'$ -\end_inset - -, - when -\begin_inset Formula $\alpha$ -\end_inset - -, - -\begin_inset Formula $\beta$ -\end_inset - -, - -\begin_inset Formula $\alpha'$ -\end_inset - -, - and -\begin_inset Formula $\beta'$ -\end_inset - - are given integers with -\begin_inset Formula $0\leq\alpha<\beta\leq m$ -\end_inset - - and -\begin_inset Formula $0\leq\alpha'<\beta'\leq m$ -\end_inset - -. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - - -\begin_inset Formula $P(x)\coloneqq\left\lfloor \frac{x-\alpha}{m}\right\rfloor -\left\lfloor \frac{x-\beta}{m}\right\rfloor $ -\end_inset - - is 1 precisely when -\begin_inset Formula $x\in[\alpha,\beta)$ -\end_inset - - and 0 for any other -\begin_inset Formula $x\in[0,1)$ -\end_inset - -. - -\begin_inset Formula $Q(x)\coloneqq\left\lfloor \frac{x-\alpha'}{m}\right\rfloor -\left\lfloor \frac{x-\beta'}{m}\right\rfloor $ -\end_inset - - works in an analogous manner. - For a linear congruential sequence given by -\begin_inset Formula $S(x)\coloneqq(ax+c)\bmod m$ -\end_inset - - that has maximum period, - the probability that -\begin_inset Formula $x_{n}\in[\alpha,\beta)\land x_{n+1}\in[\alpha',\beta')$ -\end_inset - - is -\begin_inset Formula -\begin{multline*} -\frac{1}{m}\sum_{0\leq x<m}P(x)Q(ax+c)=\\ -=\frac{1}{m}\sum_{0\leq x<m}\left(\left\lfloor \frac{x-\alpha}{m}\right\rfloor -\left\lfloor \frac{x-\beta}{m}\right\rfloor \right)\left(\left\lfloor \frac{S(x)-\alpha'}{m}\right\rfloor -\left\lfloor \frac{S(x)-\beta'}{m}\right\rfloor \right) -\end{multline*} - -\end_inset - -Now, -\begin_inset Formula -\begin{align*} -\left\lfloor \frac{x-\alpha}{m}\right\rfloor & =\frac{x}{m}-\frac{\alpha}{m}-\frac{1}{2}-\left(\left(\frac{x-\alpha}{m}\right)\right)+\frac{1}{2}\delta_{x,\alpha},\\ -\left\lfloor \frac{S(x)-\alpha'}{m}\right\rfloor & =\frac{(ax+c)\bmod m-\alpha'}{m}-\left(\left(\frac{ax+c-\alpha'}{m}\right)\right)-\frac{1}{2}+\frac{1}{2}\delta_{S(x)\alpha'}=\\ - & =\left(\left(\frac{ax+c}{m}\right)\right)-\left(\left(\frac{ax+c-\alpha'}{m}\right)\right)-\frac{\alpha'}{m}+\frac{1}{2}(\delta_{S(x)\alpha'}-\delta_{S(x)0}). -\end{align*} - -\end_inset - -Thus, - -\begin_inset Formula -\begin{multline*} -\sum_{0\leq x<m}\left\lfloor \frac{x-\alpha}{m}\right\rfloor \left\lfloor \frac{S(x)-\alpha'}{m}\right\rfloor =\\ -=\sum_{0\leq x<m}\left(\left(\frac{x}{m}-\frac{1}{2}\right)-\frac{\alpha}{m}-\left(\left(\frac{x-\alpha}{m}\right)\right)\right)\\ -\left(\left(\left(\frac{ax+c}{m}\right)\right)-\left(\left(\frac{ax+c-\alpha'}{m}\right)\right)-\frac{\alpha'}{m}\right)+\\ -+\frac{1}{2}\left(\left\lfloor \frac{S(\alpha)-\alpha'}{m}\right\rfloor +\left\lfloor \frac{S^{-1}(\alpha')-\alpha}{m}\right\rfloor -\left\lfloor \frac{S^{-1}(0)-\alpha}{m}\right\rfloor \right)+\frac{1}{4}([S(\alpha)=\alpha']-[S(\alpha)=0]). -\end{multline*} - -\end_inset - -The terms outside this last sum can be calculated directly. - Inside the sum, - we have a product of two sums with three terms each, - which we may expand into 9 terms. - For these, - note that -\begin_inset Formula $\frac{x}{m}-\frac{1}{2}=\left(\left(\frac{x}{m}\right)\right)-\frac{1}{2}[x=0]$ -\end_inset - -, - so for example -\begin_inset Formula -\[ -\sum_{0\leq x<m}\left(\frac{x}{m}-\frac{1}{2}\right)\left(\left(\frac{ax+c-\alpha'}{m}\right)\right)=\frac{1}{12}\delta(a,m,c-\alpha')-\left(\left(\frac{c-\alpha'}{m}\right)\right), -\] - -\end_inset - -and similarly, -\begin_inset Formula -\begin{multline*} -\sum_{0\leq x<m}\left(\left(\frac{x-\alpha}{m}\right)\right)\left(\left(\frac{ax+c-\alpha'}{m}\right)\right)=\\ -=\sum_{-\alpha\leq x<m-\alpha}\left(\left(\frac{x}{m}\right)\right)\left(\left(\frac{ax+c-\alpha'+\alpha}{m}\right)\right)=\frac{1}{12}\sigma(a,m,c-\alpha'+\alpha). -\end{multline*} - -\end_inset - -The other terms do not include sawtooth functions and can be expanded mechanically using that -\begin_inset Formula $\sum_{0\leq x<m}x=\frac{m(m-1)}{2}$ -\end_inset - -. - Then we can compute the initial sum as the sum of 4 of these sums. -\end_layout - -\begin_layout Subsubsection -Second Set -\end_layout - -\begin_layout Standard -In many cases, - exact computations with integers are quite difficult to carry out, - but we can attempt to study the probabilities that arise when we take the average real values of -\begin_inset Formula $x$ -\end_inset - - instead of restricting the calculation to integer values. - Although these results are only approximate, - they shed some light on the subject. -\end_layout - -\begin_layout Standard -It is convenient to deal with numbers -\begin_inset Formula $U_{n}$ -\end_inset - - between zero and one; - for linear congruential sequences, - -\begin_inset Formula $U_{n}=X_{n}/m$ -\end_inset - -, - and we have -\begin_inset Formula $U_{n+1}=\{aU_{n}+\theta\}$ -\end_inset - -, - where -\begin_inset Formula $\theta=c/m$ -\end_inset - - and -\begin_inset Formula $\{x\}$ -\end_inset - - denotes -\begin_inset Formula $x\bmod1$ -\end_inset - -. - For example, - the formula for serial correlation now becomes -\begin_inset Formula -\[ -C=\left(\int_{0}^{1}x\{ax+\theta\}\text{d}x-\left(\int_{0}^{1}x\text{d}x\right)^{2}\right)\biggg/\left(\int_{0}^{1}x^{2}\text{d}x-\left(\int_{0}^{1}x\text{d}x\right)^{2}\right). -\] - -\end_inset - - -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc21[HM23] -\end_layout - -\end_inset - -(R. - R. - Coveyou.) What is the value of -\begin_inset Formula $C$ -\end_inset - - in the formula just given? -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -We have -\begin_inset Formula -\begin{align*} -\int_{0}^{1}x\text{d}x & =\left.\frac{x^{2}}{2}\right|_{x=0}^{1}=\frac{1}{2}, & \int_{0}^{1}x^{2}\text{d}x & =\left.\frac{x^{3}}{3}\right|_{x=0}^{1}=\frac{1}{3}, -\end{align*} - -\end_inset - -and we just need to calculate the more complex integral. - Assume -\begin_inset Formula $a>0$ -\end_inset - -. - Then the graph for -\begin_inset Formula $\{ax+\theta\}$ -\end_inset - - is a sequence of lines. - The first goes from -\begin_inset Formula $(0,\theta)$ -\end_inset - - to -\begin_inset Formula $(\frac{1-\theta}{a},1)$ -\end_inset - -, - the next one from -\begin_inset Formula $(\frac{1-\theta}{a},0)$ -\end_inset - - to -\begin_inset Formula $(\frac{2-\theta}{a},1)$ -\end_inset - -, - etc., - and the last one goes from -\begin_inset Formula $(1-\tfrac{\theta}{a},0)$ -\end_inset - - to -\begin_inset Formula $(1,\theta)$ -\end_inset - - (we used that -\begin_inset Formula $a$ -\end_inset - - is an integer to calculate this). - Thus -\begin_inset Formula -\[ -\int_{0}^{1}x\{ax+\theta\}\text{d}x=\sum_{k=1}^{a-1}\int_{\frac{k-\theta}{a}}^{\frac{k+1-\theta}{a}}x(ax+\theta-k)\text{d}x+\int_{0}^{\frac{1-\theta}{a}}x(ax+\theta)\text{d}x+\int_{1-\frac{\theta}{a}}^{1}x(ax+\theta-a)\text{d}x. -\] - -\end_inset - -Now, -\begin_inset Formula -\[ -\int x(ax+\theta-k)\text{d}x=\frac{a}{3}x^{3}+\frac{\theta-k}{2}x^{2}+C, -\] - -\end_inset - -so if we call -\begin_inset Formula $x_{k}\coloneqq\frac{k-\theta}{a}$ -\end_inset - - except that -\begin_inset Formula $x_{0}\coloneqq0$ -\end_inset - - and -\begin_inset Formula $x_{a+1}\coloneqq1$ -\end_inset - -, - we have -\begin_inset Formula -\begin{multline*} -\int_{0}^{1}x\{ax+\theta\}\text{d}x=\sum_{0\leq k\leq a}\int_{x_{k}}^{x_{k+1}}x(ax+\theta-k)\text{d}x=\\ -=\sum_{0\leq k\leq a}\left(\frac{a}{3}x_{k+1}^{3}+\frac{\theta-k}{2}x_{k+1}^{2}-\frac{a}{3}x_{k}^{3}-\frac{\theta-k}{2}x_{k}^{2}\right)=\frac{a}{3}+\frac{\theta-a}{2}+\sum_{0<k\leq a}\frac{1}{2}x_{k}^{2}=\\ -=\frac{a}{3}+\frac{\theta-a}{2}+\frac{1}{2a^{2}}\sum_{k=1}^{a}(k^{2}-2k\theta+\theta^{2})=\frac{\theta}{2}-\frac{a}{6}+\frac{(a+1)(2a+1)}{12a}-\frac{(a+1)\theta}{2a}+\frac{\theta^{2}}{2a}=\\ -=\frac{\theta(\theta-1)}{2a}+\frac{1}{12a}+\frac{1}{4}. -\end{multline*} - -\end_inset - -Putting it all together, -\begin_inset Formula -\[ -C=\left(\frac{\theta(\theta-1)}{2a}+\frac{1}{12a}+\frac{1}{4}-\frac{1}{4}\right)\biggg/\left(\frac{1}{3}-\frac{1}{4}\right)=\frac{6\theta(\theta-1)+1}{a}. -\] - -\end_inset - - -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc22[M22] -\end_layout - -\end_inset - -Let -\begin_inset Formula $a$ -\end_inset - - be an integer, - and let -\begin_inset Formula $0\leq\theta<1$ -\end_inset - -. - If -\begin_inset Formula $x$ -\end_inset - - is a random real number, - uniformly distributed between 0 and 1, - and if -\begin_inset Formula $s(x)=\{ax+\theta\}$ -\end_inset - -, - what is the probability that -\begin_inset Formula $s(x)<x$ -\end_inset - -? - (This is the -\begin_inset Quotes eld -\end_inset - -real number -\begin_inset Quotes erd -\end_inset - - analog of Theorem P.) -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -As in the previous exercise, - let -\begin_inset Formula $x_{0}\coloneqq0$ -\end_inset - -, - -\begin_inset Formula $x_{k}\coloneqq\frac{k-\theta}{a}$ -\end_inset - - for -\begin_inset Formula $k\in\{1,\dots,a\}$ -\end_inset - -, - and -\begin_inset Formula $x_{a+1}\coloneqq1$ -\end_inset - -, - for -\begin_inset Formula $k\in\{0,\dots,a\}$ -\end_inset - - and -\begin_inset Formula $x\in[x_{k},x_{k+1})$ -\end_inset - - we have -\begin_inset Formula $\lfloor ax+\theta\rfloor=k$ -\end_inset - - and -\begin_inset Formula -\[ -s(x)=ax+\theta-\lfloor ax+\theta\rfloor<x\iff(a-1)x<\lfloor ax+\theta\rfloor-\theta=k-\theta\iff x<\frac{k-\theta}{a-1}, -\] - -\end_inset - -so in particular -\begin_inset Formula $s(x)\geq x$ -\end_inset - - for -\begin_inset Formula $x<x_{1}$ -\end_inset - - and the probability is -\begin_inset Formula -\begin{multline*} -\int_{0}^{1}[s(x)<x]\text{d}x=\sum_{k=1}^{a}\int_{x_{k}}^{x_{k+1}}[x<\tfrac{k-\theta}{a-1}]\text{d}x=\sum_{k=1}^{a-1}\left(\frac{k-\theta}{a-1}-\frac{k-\theta}{a}\right)+1-\frac{a-\theta}{a}=\\ -=\sum_{k=1}^{a-1}\frac{k-\theta}{a(a-1)}+\frac{\theta}{a}=\left(\frac{1}{2}-\frac{\theta}{a}\right)+\frac{\theta}{a}=\frac{1}{2}. -\end{multline*} - -\end_inset - - -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc25[M25] -\end_layout - -\end_inset - -Let -\begin_inset Formula $\alpha$ -\end_inset - -, - -\begin_inset Formula $\beta$ -\end_inset - -, - -\begin_inset Formula $\alpha'$ -\end_inset - -, - -\begin_inset Formula $\beta'$ -\end_inset - - be real numbers with -\begin_inset Formula $0\leq\alpha<\beta\leq1$ -\end_inset - -, - -\begin_inset Formula $0\leq\alpha'<\beta'\leq1$ -\end_inset - -. - Under the assumptions of exercise 22, - what is the probability that -\begin_inset Formula $\alpha\leq x<\beta$ -\end_inset - - and -\begin_inset Formula $\alpha'\leq s(x)<\beta'$ -\end_inset - -? - (This is the -\begin_inset Quotes eld -\end_inset - -real number -\begin_inset Quotes erd -\end_inset - - analog of exercise 19.) -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -In the notation of the answer to exercise 22, - assume that -\begin_inset Formula $\alpha\in[x_{p},x_{p+1})$ -\end_inset - - and -\begin_inset Formula $\beta\in[x_{q},x_{q+1})$ -\end_inset - -, - with -\begin_inset Formula $0\leq p\leq q\leq a$ -\end_inset - -. - For -\begin_inset Formula $x\in[x_{k},x_{k+1})$ -\end_inset - -, -\begin_inset Formula -\[ -\alpha'\leq s(x)<\beta'\iff\alpha'\leq ax+\theta-k<\beta'\iff x\in\left[\frac{\alpha'+k-\theta}{a},\frac{\beta'+k-\theta}{a}\right). -\] - -\end_inset - -Note that, - since -\begin_inset Formula $s(x)$ -\end_inset - - goes from 0 to 1 when -\begin_inset Formula $x$ -\end_inset - - goes from -\begin_inset Formula $x_{k}$ -\end_inset - - to -\begin_inset Formula $x_{k+1}$ -\end_inset - -, - each of these intervals has -\begin_inset Formula $s(x)$ -\end_inset - - enter and exit -\begin_inset Formula $[\alpha',\beta')$ -\end_inset - - and fully contains the interval above. - Let -\begin_inset Formula $s_{k}^{-1}(y)\coloneqq\frac{y+k-\theta}{a}$ -\end_inset - -. - If -\begin_inset Formula $p=q$ -\end_inset - -, - the probability is -\begin_inset Formula -\[ -\int_{\alpha}^{\beta}[\alpha'\leq s(x)<\beta']\text{d}x=\max\left\{ 0,\min\{\beta,s_{p}^{-1}(\beta')\}-\max\{\alpha,s_{p}^{-1}(\alpha')\}\right\} . -\] - -\end_inset - -If -\begin_inset Formula $p\neq q$ -\end_inset - -, - we have to consider the two extremes and the -\begin_inset Formula $q-p-1$ -\end_inset - - intervals in the middle, - each of which contributes -\begin_inset Formula $\frac{\beta'-\alpha'}{a}$ -\end_inset - -, - so the probability in this case is -\begin_inset Formula -\begin{multline*} -\max\left\{ 0,s_{p}^{-1}(\beta')-\max\{\alpha,s_{p}^{-1}(\alpha')\}\right\} +(q-p-1)\frac{\beta'-\alpha'}{a}+\\ -+\max\left\{ 0,\min\{\beta,s_{q}^{-1}(\beta')\}-s_{q}^{-1}(\alpha')\right\} . -\end{multline*} - -\end_inset - -Note that this last formula is still valid when -\begin_inset Formula $p=q$ -\end_inset - -. -\end_layout - -\end_body -\end_document |
