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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 /1.2.7.lyx | |
| parent | 16ccda6c459c0fd7ca2081e9d541124c28b0c556 (diff) | |
Changed layout for more manageable volumes
Diffstat (limited to '1.2.7.lyx')
| -rw-r--r-- | 1.2.7.lyx | 572 |
1 files changed, 0 insertions, 572 deletions
diff --git a/1.2.7.lyx b/1.2.7.lyx deleted file mode 100644 index f110304..0000000 --- a/1.2.7.lyx +++ /dev/null @@ -1,572 +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 -\usepackage{amsmath} -\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 -exerc1[01] -\end_layout - -\end_inset - -What are -\begin_inset Formula $H_{0}$ -\end_inset - -, - -\begin_inset Formula $H_{1}$ -\end_inset - -, - and -\begin_inset Formula $H_{2}$ -\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 $H_{0}=0$ -\end_inset - -, - -\begin_inset Formula $H_{1}=1$ -\end_inset - -, - -\begin_inset Formula $H_{2}=\frac{3}{2}$ -\end_inset - -. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc4[10] -\end_layout - -\end_inset - -Decide which of the following statements are true for all positive integers -\begin_inset Formula $n$ -\end_inset - -: -\end_layout - -\begin_layout Enumerate -\begin_inset Formula $H_{n}<\ln n$ -\end_inset - -. -\end_layout - -\begin_layout Enumerate -\begin_inset Formula $H_{n}>\ln n$ -\end_inset - -. -\end_layout - -\begin_layout Enumerate -\begin_inset Formula $H_{n}>\ln n+\gamma$ -\end_inset - -. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - - -\end_layout - -\begin_layout Enumerate -False, - since -\begin_inset Formula $H_{2}=\frac{3}{2}>1>\ln2$ -\end_inset - -. -\end_layout - -\begin_layout Enumerate -True, - because the next one is true. -\end_layout - -\begin_layout Enumerate -True. - If this wasn't true for some number -\begin_inset Formula $n$ -\end_inset - -, - then it would be -\begin_inset Formula -\[ -0\geq H_{n}-(\ln n+\gamma)>\frac{1}{2n}-\frac{1}{12n^{2}}+\frac{1}{12n^{4}}-\frac{1}{252n^{6}}, -\] - -\end_inset - -but -\begin_inset Formula $\frac{1}{2n}>\frac{1}{12n^{2}}$ -\end_inset - - and -\begin_inset Formula $\frac{1}{12n^{4}}>\frac{1}{252n^{6}}$ -\end_inset - - for any -\begin_inset Formula $n\geq1\#$ -\end_inset - -. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc9[M18] -\end_layout - -\end_inset - -Theorem A applies only when -\begin_inset Formula $x>0$ -\end_inset - -; - what is the value of the sum considered when -\begin_inset Formula $x=-1$ -\end_inset - -? -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - -Using Equation 1.2.6(18) in -\begin_inset Formula $(*)$ -\end_inset - - and Exercise 1.2.6–48 in -\begin_inset Formula $(**)$ -\end_inset - -, -\begin_inset Formula -\begin{multline*} -\sum_{k=1}^{n}\binom{n}{k}(-1)^{k}H_{k}=\sum_{1\leq j\leq k\leq n}\binom{n}{k}(-1)^{k}\frac{1}{j}=\sum_{j=1}^{n}\frac{1}{j}\sum_{k=j}^{n}\binom{n}{k}(-1)^{k}=\\ -=(-1)^{n}\sum_{j=1}^{n}\frac{1}{j}\sum_{k=0}^{n-j}\binom{n}{k}(-1)^{k}\overset{(*)}{=}(-1)^{\cancel{n}}\sum_{j=1}^{n}\frac{1}{j}(-1)^{\cancel{n}-j}\binom{n-1}{n-j}=\\ -=\sum_{j=0}^{n}\frac{1}{j+1}(-1)^{-j-1}\binom{n-1}{n-j-1}=-\sum_{j=0}^{n-1}\frac{(-1)^{j}}{j+1}\binom{n-1}{j}\overset{(**)}{=}\frac{1}{\binom{n}{n-1}}=-\frac{1}{n}. -\end{multline*} - -\end_inset - - -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc11[M21] -\end_layout - -\end_inset - -Using summation by parts, - evaluate -\begin_inset Formula -\[ -\sum_{1<k\leq n}\frac{1}{k(k-1)}H_{k}. -\] - -\end_inset - - -\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 -\[ -\frac{1}{k(k-1)}H_{k}=\left(\frac{1}{k-1}-\frac{1}{k}\right)H_{k}=\frac{1}{k-1}\left(H_{k-1}+\frac{1}{k}\right)-\frac{1}{k}H_{k}, -\] - -\end_inset - -so -\begin_inset Formula -\begin{multline*} -\sum_{k=2}^{n}\frac{H_{k}}{k(k-1)}=\sum_{k=2}^{n}\left(\frac{1}{k-1}\left(H_{k-1}+\frac{1}{k}\right)-\frac{1}{k}H_{k}\right)=1-\frac{1}{n}H_{n}+\sum_{k=2}^{n}\frac{1}{k(k-1)}=\\ -=1-\frac{H_{n}}{n}+\sum_{k=2}^{n}\left(\frac{1}{k-1}-\frac{1}{k}\right)=1-\frac{H_{n}}{n}+H_{n-1}-H_{n}+1=\\ -=1-\frac{1}{n}H_{n}\cancel{+H_{n}}-\frac{1}{n}\cancel{-H_{n}}+1=2-\frac{1}{n}(1+H_{n}). -\end{multline*} - -\end_inset - - -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc12[M10] -\end_layout - -\end_inset - -Evaluate -\begin_inset Formula $H_{\infty}^{(1000)}$ -\end_inset - - correct to at least 100 decimal places. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -answer -\end_layout - -\end_inset - - -\begin_inset Formula -\[ -H_{\infty}^{(1000)}=\sum_{k\geq1}\frac{1}{k^{1000}}=1\pm0.5\cdot10^{-100}, -\] - -\end_inset - -since -\begin_inset Formula $2^{1000}$ -\end_inset - - has way more than 100 digits. -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc15[M23] -\end_layout - -\end_inset - -Express -\begin_inset Formula $\sum_{k=1}^{n}H_{k}^{2}$ -\end_inset - - in terms of -\begin_inset Formula $n$ -\end_inset - - and -\begin_inset Formula $H_{n}$ -\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 -\begin{align*} -\sum_{k=1}^{n}H_{k}^{2} & =\sum_{1\leq j\leq k\leq n}\frac{1}{j}H_{k}=\sum_{j=1}^{n}\frac{1}{j}\sum_{k=j}^{n}H_{k}=\sum_{j=1}^{n}\frac{1}{j}\left(\sum_{k=1}^{n}H_{k}-\sum_{k=1}^{j-1}H_{k}\right)\\ - & =\sum_{j=1}^{n}\frac{1}{j}\left((n+1)H_{n}-n-jH_{j-1}+j-1\right)\\ - & =\sum_{j=1}^{n}\left(\frac{1}{j}\left((n+1)H_{n}-n-1\right)-H_{j-1}+1\right)\\ - & =\left((n+1)H_{n}-n-1\right)H_{n}-(nH_{n-1}-n+1)+n\\ - & =(n+1)H_{n}^{2}-(n+1)H_{n}-nH_{n}+n+n\\ - & =(n+1)H_{n}^{2}-(2n+1)H_{n}+2n. -\end{align*} - -\end_inset - - -\end_layout - -\begin_layout Standard -\begin_inset ERT -status open - -\begin_layout Plain Layout - - -\backslash -rexerc23[HM20] -\end_layout - -\end_inset - -By considering the function -\begin_inset Formula $\Gamma'(x)/\Gamma(x)$ -\end_inset - -, - generalize -\begin_inset Formula $H_{n}$ -\end_inset - - to noninteger values of -\begin_inset Formula $n$ -\end_inset - -. - You may use the fact that -\begin_inset Formula $\Gamma'(1)=-\gamma$ -\end_inset - -, - anticipating the next exercise. -\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{multline*} -\Gamma'(x)=\lim_{m}\left(\frac{\ln m\cdot m^{x}m!}{x(x+1)\cdots(x+m)}-\frac{m^{x}m!\sum_{k=0}^{m}\frac{x(x+1)\cdots(x+m)}{(x+k)}}{(x(x+1)\cdots(x+m))^{2}}\right)=\\ -=\Gamma(x)\lim_{m}\left(\ln m-\sum_{k=0}^{m}\frac{1}{x+k}\right)=\Gamma(x)(\ln m-H_{k+m}+H_{k-1}). -\end{multline*} - -\end_inset - -The fact given in the exercise tells us that -\begin_inset Formula -\[ --\gamma=\Gamma'(1)=\Gamma(1)\lim_{m}(\ln m-H_{m+1}), -\] - -\end_inset - -so for -\begin_inset Formula $n\in\mathbb{Z}^{>0}$ -\end_inset - -, -\begin_inset Formula -\[ -\frac{\Gamma'(n)}{\Gamma(n)}=\lim_{m}(\ln m-H_{n+m}+H_{n-1})=H_{n-1}-\gamma, -\] - -\end_inset - -and we can define -\begin_inset Formula -\[ -H_{x}\coloneqq\frac{\Gamma'(x+1)}{\Gamma(x+1)}+\gamma -\] - -\end_inset - -for any -\begin_inset Formula $x\in\mathbb{C}$ -\end_inset - - where this expression is defined or can be extended by continuity. -\end_layout - -\end_body -\end_document |
