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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 /3.2.2.lyx | |
| parent | 16ccda6c459c0fd7ca2081e9d541124c28b0c556 (diff) | |
Changed layout for more manageable volumes
Diffstat (limited to '3.2.2.lyx')
| -rw-r--r-- | 3.2.2.lyx | 834 |
1 files changed, 0 insertions, 834 deletions
diff --git a/3.2.2.lyx b/3.2.2.lyx deleted file mode 100644 index 173f721..0000000 --- a/3.2.2.lyx +++ /dev/null @@ -1,834 +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 Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc1[12] -\end_layout - -\end_inset - -In practice, - we form random numbers using -\begin_inset Formula $X_{n+1}=(aX_{n}+c)\bmod m$ -\end_inset - -, - where the -\begin_inset Formula $X$ -\end_inset - -'s are -\emph on -integers -\emph default -, - afterwards treating them as the -\emph on -fractions -\emph default - -\begin_inset Formula $U_{n}=X_{n}/m$ -\end_inset - -. - The recurrence relation for -\begin_inset Formula $U_{n}$ -\end_inset - - is actually -\begin_inset Formula -\[ -U_{n+1}=(aU_{n}+c/m)\bmod1. -\] - -\end_inset - -Discuss the generation of random sequences using this relation -\emph on -directly -\emph default -, - by making use of floating point arithmetic on the computer. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -Despite the appeal of the idea for simplicity, - there is the problem of precision, - as the computer needs to be able to represent numbers as high as -\begin_inset Formula $a$ -\end_inset - - (almost) with a precision of -\begin_inset Formula $1/m$ -\end_inset - -; - otherwise some numbers would be truncated and the period would be smaller than expected. - Also, - there might be issues due to rounding if -\begin_inset Formula $m$ -\end_inset - - is not a divisor of a power of the computer's base (i.e. - 2, - or in some old computers 10), - but if it is, - then it's just faster to use integer arithmetic. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc2[M20] -\end_layout - -\end_inset - -A good source of random numbers will have -\begin_inset Formula $X_{n-1}<X_{n+1}<X_{n}$ -\end_inset - - about one-sixth of the time, - since each of the six possible relative orders of -\begin_inset Formula $X_{n-1}$ -\end_inset - -, - -\begin_inset Formula $X_{n}$ -\end_inset - -, - and -\begin_inset Formula $X_{n+1}$ -\end_inset - - should be equally probable. - However, - show that the ordering above -\emph on -never -\emph default - occurs if the Fibonacci sequence (5) is used. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -If -\begin_inset Formula $X_{n+1}<X_{n}$ -\end_inset - -, - then -\begin_inset Formula $X_{n-1}=(X_{n+1}-X_{n})\bmod m=X_{n+1}-X_{n}+m>X_{n+1}$ -\end_inset - -. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -exerc4[00] -\end_layout - -\end_inset - -Why is the most significant byte used in the first line of program (14), - instead of some other byte? -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -It follows Algorithm B, - and it's the byte that's the most random. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc5[20] -\end_layout - -\end_inset - -Discuss using -\begin_inset Formula $X_{n}=Y_{n}$ -\end_inset - - in Algorithm M, - in order to improve the speed of generation. - Is the result analogous to Algorithm B? -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -This would use the next element in the sequence to choose which of the previous elements to use. - By the discussion about Exercise 15, - the period of the sequence would be the same as the original one, - and the resulting might actually be less random. - This is different than Algorithm B where the element used to choose is the one that was chosen from the table in the previous iteration, - so the index -\begin_inset Formula $j$ -\end_inset - - itself is shuffled. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -exerc6[10] -\end_layout - -\end_inset - -In the binary method (10), - the text states that the low-order bit of -\family typewriter -X -\family default - is random, - if the code is performed repeatedly. - Why isn't the entire -\emph on -word -\emph default - -\family typewriter -X -\family default - random? -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -Because there is a high correlation between one element and the next: - if the higher order bit is 0, - the next word is simply twice the previous one. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc9[M24] -\end_layout - -\end_inset - -(R. - R. - Coveyou.) Use the result of exercise 8 to prove that the modified middle-square method (4) has a period of length -\begin_inset Formula $2^{e-2}$ -\end_inset - -. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -After several trials of the middle-square method, - we hypothesize that, - when -\begin_inset Formula $e\geq2$ -\end_inset - -, - -\begin_inset Formula $X_{n}=4Y_{n}+2$ -\end_inset - - for each -\begin_inset Formula $n\geq0$ -\end_inset - -, - where -\begin_inset Formula $(Y_{n})_{n}$ -\end_inset - - is the quadratic congruential sequence given by -\begin_inset Formula -\begin{align*} -X_{0} & =4Y_{0}+2, & Y_{n+1} & =(4Y_{n}+1)(Y_{n}+1)\bmod2^{e-2}. -\end{align*} - -\end_inset - -This sequence has -\begin_inset Formula $d=4$ -\end_inset - -, - -\begin_inset Formula $a=5$ -\end_inset - -, - and -\begin_inset Formula $c=1$ -\end_inset - -, - so it meets the conditions from exercise 8 and therefore has period -\begin_inset Formula $2^{e-2}$ -\end_inset - -. - We can prove this identity by induction, - as if -\begin_inset Formula $X_{n}=4Y_{n}+2$ -\end_inset - -, - then -\begin_inset Formula -\begin{multline*} -X_{n+1}=X_{n}(X_{n}+1)\bmod2^{e}=(4Y_{n}+2)(4Y_{n}+3)\bmod2^{e}=\\ -=16Y_{n}^{2}+20Y_{n}+6\bmod2^{e}=4(4Y_{n}+1)(Y_{n}+1)+2\bmod2^{e}=4Y_{n+1}+2. -\end{multline*} - -\end_inset - - -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc22[M24] -\end_layout - -\end_inset - -The text restricts discussion of the extended linear sequences (8) to the case that -\begin_inset Formula $m$ -\end_inset - - is prime. - Prove that reasonably long periods can also be obtained when -\begin_inset Formula $m$ -\end_inset - - is -\begin_inset Quotes eld -\end_inset - -squarefree, -\begin_inset Quotes erd -\end_inset - - that is, - the product of distinct primes. - (Examinations of Table 3.2.1.1–1 shows that -\begin_inset Formula $m=w\pm1$ -\end_inset - - often satisfies this hypothesis; - many of the results of the text can therefore be carried over to that case, - which is somewhat more convenient for calculation.) -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -If -\begin_inset Formula $m=p_{1}\cdots p_{t}$ -\end_inset - - where the -\begin_inset Formula $p_{k}$ -\end_inset - - are distinct primes, - then integers -\begin_inset Formula $a\in\{0,\dots,m-1\}$ -\end_inset - - can be associated with the tuples -\begin_inset Formula $(a\bmod p_{1},\dots,a\bmod p_{t})$ -\end_inset - - because of the Chinese remainder theorem. - Furthermore, - equation (8) respects this association, - in the sense that -\begin_inset Formula $X_{n}\bmod p_{i}=((a_{1}\bmod p_{i})(X_{n-1}\bmod p_{i})+\dots+(a_{k}\bmod p_{i})(X_{n-k}\bmod p_{i}))\bmod p_{i}$ -\end_inset - - and therefore we could as well calculate the sequence using these -\begin_inset Quotes eld -\end_inset - -coordinates -\begin_inset Quotes erd -\end_inset - -. - We also know that the -\begin_inset Formula $a_{j}\bmod p_{i}$ -\end_inset - - can be chosen to make -\begin_inset Formula $(X_{n}\bmod p_{i})_{n}$ -\end_inset - - have period -\begin_inset Formula $p_{i}^{k}-1$ -\end_inset - -, - so the -\begin_inset Formula $a_{j}$ -\end_inset - - can be chosen to make -\begin_inset Formula $(X_{n})_{n}$ -\end_inset - - have period -\begin_inset Formula $\text{lcm}\{p_{1}^{k}-1,\dots,p_{t}^{k}-1\}$ -\end_inset - -, - which we deem reasonably long. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -exerc23[20] -\end_layout - -\end_inset - -Discuss the sequence defined by -\begin_inset Formula $X_{n}=(X_{n-55}-X_{n-24})\bmod m$ -\end_inset - - as an alternative to (7). -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -The period is still at least -\begin_inset Formula $2^{55}-1$ -\end_inset - -, - since the sequence defined by the lowest bit in (7) has this period and the one defined by the lowest bit in this formula is exactly the same. - We don't know if exercise 30 still applies as we haven't done it. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -begin{samepage} -\end_layout - -\end_inset - - -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc33[M23] -\end_layout - -\end_inset - - -\end_layout - -\begin_layout Enumerate -Let -\begin_inset Formula $g_{n}(z)=X_{n+30}+X_{n+29}z+\dots+X_{n}z^{30}+X_{n+54}z^{31}+\dots+X_{n+31}z^{54}$ -\end_inset - -, - where the -\begin_inset Formula $X$ -\end_inset - -'s satisfy the lagged Fibonacci recurrence (7). - Find a simple relation between -\begin_inset Formula $g_{n}(z)$ -\end_inset - - and -\begin_inset Formula $g_{n+t}(z)$ -\end_inset - -. -\end_layout - -\begin_layout Enumerate -Express -\begin_inset Formula $X_{500}$ -\end_inset - - in terms of -\begin_inset Formula $X_{0},\dots,X_{54}$ -\end_inset - -. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -end{samepage} -\end_layout - -\end_inset - - -\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 obviously had to look at the answers.) -\end_layout - -\end_inset - - -\end_layout - -\begin_layout Enumerate -\begin_inset Formula -\begin{align*} -g_{n+1}(z) & =X_{n+31}+X_{n+30}z+\dots+X_{n+1}z^{30}+X_{n+55}z^{31}+\dots+X_{n+32}z^{54}\\ - & =zg_{n}(z)+X_{n+31}-X_{n}z^{31}+X_{n+55}z^{31}-X_{n+31}z^{55}\\ - & =zg_{n}(z)+X_{n+31}(z^{31}-z^{55}+1)+km, -\end{align*} - -\end_inset - -for some small integer -\begin_inset Formula $k$ -\end_inset - -. - If we see the -\begin_inset Formula $g_{n}$ -\end_inset - - as polynomials on -\begin_inset Formula $z$ -\end_inset - -, - in the domain -\begin_inset Formula $\mathbb{Z}[X]$ -\end_inset - -, - then -\begin_inset Formula $g_{n+t}(z)\equiv z^{t}g_{n}(z)$ -\end_inset - - in -\begin_inset Formula $A\coloneqq\mathbb{Z}[X]/(m\mathbb{Z}[X]+(z^{55}-z^{31}-1)\mathbb{Z}[X])\cong\mathbb{Z}_{m}[X]/(z^{55}-z^{31}-1)\mathbb{Z}_{m}[X]$ -\end_inset - -. -\end_layout - -\begin_layout Enumerate -We prove by strong induction that, - if -\begin_inset Formula $a_{0}+\dots+a_{54}z^{54}=z^{k}\bmod(z^{55}-z^{31}-1)$ -\end_inset - - in -\begin_inset Formula $\mathbb{Z}_{m}[X]$ -\end_inset - -, - then -\begin_inset Formula $X_{k}=a_{0}X_{0}+\dots+a_{54}X^{54}\bmod m$ -\end_inset - -. - If -\begin_inset Formula $k<55$ -\end_inset - -, - this is obvious; - otherwise -\begin_inset Formula $X_{k}=X_{k-55}+X_{k-24}$ -\end_inset - - and -\begin_inset Formula $z^{k}\bmod(z^{55}-z^{31}-1)=(z^{k-55}+z^{k-24})\bmod(z^{55}-z^{31}-1)$ -\end_inset - - by the division algorithm. - With this, - we run -\family typewriter -divide(z^500, - z^55-z^31-1, - z) -\family default - in Maxima and we get that -\begin_inset Formula $X_{500}=120X_{54}+462X_{50}+455X_{57}+X_{44}+120X_{43}+1001X_{40}+18X_{37}+9X_{36}+1287X_{33}+16X_{30}+462X_{26}+105X_{23}+210X_{19}+364X_{16}+X_{13}+36X_{12}+715X_{9}+17X_{6}+X_{5}+792X_{2}\bmod m$ -\end_inset - -. -\end_layout - -\end_body -\end_document |
