I'm teaching a class in which I want to demonstrate to my students that queries are not guaranteed to return results in a specific order without an explicit ORDER BY. I've observed that SQL Server seems to return ordered results even when ORDER BY is not present in the query. This is a problem because I'm concerned that my students will become confused on this point.  Examples of observed behaviour:   By default, data appears to be ordered in primary key order, even if the primary key is nonclustered. If I use GROUP BY, the result set appears to be in order of the last column. For example GROUP BY this, that ends up with the data in order of that, which is weird, especially if there is no index on it.   I haven't observed this behavior in other databases such as MySQL, PostgreSQL and SQLite. Is there something fundamentally different about SQL Server which causes it to order results for some queries even without an ORDER BY?   Now it seems to me that ordering the data when not asked is an extra unnecessary step which wastes processing time. Is that true?  And is there some kind of global setting that disables this behavior? Is there a way to get SQL Server to stop ordering data?  It also makes it harder to demonstrate to students that data is not automatically ordered.  Can anyone give me a simple demo script that shows the order of the results changing from execution to execution?
We all know that a simple statement such as:  SELECT * FROM stuff;   should not produce an ordered result. However, when I try to demonstrate this, it always comes out in primary key order.  Moreover a statement such as:  SELECT thing,whatever FROM stuff GROUP BY thing,whatever;   always appears to sort thing by the last field in the GROUP BY clause, which is not at all helpful.  The question is, under what circumstances does SQL SERVER order the result even if unasked, and what can I do to stop this?  I am trying to demonstrate to my students that order is indeterminate unless specified, but this is not helping my case.  I admit that I am working with a small set of sample data.  Thanks
I am currently working on a model which takes two parameters and produces a measurement statistic. Think of it as Z = f(X,Y).   Z is a matrix of my statistics and I am creating a surface plot of it in matlab. Basically, I am looking for a mathematical/analytical way of determining if the surface is smooth, or if it is jagged. Do large values tend to be clustered together or are they dispersed throughout the matrix? - that is my question. Basically, how mixed up are the values of my matrix?  I need to run the model over different parameter sets and I want to be able to analytically determine which one of my surfaces is the smoothest, has the greatest clustering of large values, and ideally, has no negative values.   Any help will be greatly appreciated and please let me know if you need any further information.   Cheers I'm using Ubuntu 17.10 with GNOME shell and Numix-Circle icon theme.   When I hover over the Numix icon for Nightly Web Browser, which is pinned to the dock I get the title "Nightly Web Browser".      But when I launch the program, another icon pops up at the bottom, with the name "Nightly". Electric charge is lorentz invariant I know that electric charge is lorentz invariant quantity and I can easily think of experiment to check that. Is a though experiment that can prove that also? Why is the direction of cross products of two vectors perpendicular to the plane? Booting Ubuntu Failure : error: attempt to read or write outside of disk 'hd0' I have installed Ubuntu 12.10 in a Western Digital external hard drive (320GB). This is a complete installation, not a live USB.  When I plug it in my HP desktop I go to the BIOS settings and boot off the hard drive, everything work perfectly as it should. Now this works on every single computer and laptop in my house (all HP), except for ONE. My HP ProBook 4530s.  When I select to boot of the USB I get the message:  error: attempt to read or write outside of disk 'hd0'   Now, I have removed the hard drive from my laptop and the external drive is the ONLY drive plugged in. Below is a screenshot of the message on the screen. After the message I navigate to ls / (as shown below):    After here I try to acces other folders under ls /, for example, I try to go to ls /boot to get to the grub folder. Then I get the same message as before: as shown below:    grub rescue&gt; ls /boot  error: attempt to read or write outside of disk 'hd0' grub rescue&gt; _   The only folders I can access without getting the message again are /home, /run and /usr.   So how do I:   Boot Ubuntu from GRUB2 (this screen) manually Set to automatically boot Ubuntu If possible an explanation for this problem   Thanks! Cyrillic monospaced font in XeLaTeX I've installed full TexLive 2011 using "install-tl" script in Ubuntu 12.04.  When I was using TexLive 2009 from repositories the following file was compiled without any errors.  \documentclass{article} % XeLaTeX \usepackage{xltxtra} \usepackage{xunicode}  % Fonts \setmainfont{Arial} \newfontfamily\cyrillicfont{Arial} \setmonofont{Courier New}  % Lang \usepackage{polyglossia} \setmainlanguage{russian} \setotherlanguage{english}  \begin{document} English normal.  \texttt{English monospace}.  Русский обычный.  \texttt{Русский моноширинный}.  % Text in Russian \end{document}   But XeLaTeX from TexLive 2011 gives this error:     ERROR: Package polyglossia Error:       --- TeX said ---   The current roman font does not contain the Cyrillic script!   Please define \cyrillicfont with \newfontfamily.      See the polyglossia package documentation for explanation.   Type  H   for immediate help.    ...                                                    l.17 ...nglish normal.  \texttt{English monospace}                                                     .   In spite of this error the output PDF is correct.  The error remains if comment out \setmonofont{Courier New}.  Using Courier New as main font gives no error on normal text (without \texttt, \textbf and so on).  Using DejaVu Sans Mono as monospaced font gives no error too.  I've been searching for solution few hours but there aren't any.  Maybe this is a bug in Polyglossia or Fontspec? What's the difference between  and ,  and ? What's the difference between &lt;b&gt; and &lt;strong&gt;, &lt;i&gt; and &lt;em&gt; in HTML/XHTML? When should you use each? What is data blending? This term appears frequently in the .  Is blending a specific method in data-mining and statistical learning? I cannot get a relevant result from google.  It seems blending is mixing up outcomes from many models and resulting in a better result. Is there any resource that helps me knowing more about it? Windows 8 upgrade Recovery Disk I have upgraded to Windows 8 from Win 7. I want to create a recovery disk for Windows 8, just in case something goes wrong. I didn't find the option of creating it from the control panel.  How do I create a Recovery CD/DVD? I'm using Ubuntu GNOME 16.10 and was trying to install WPS Office. I tried to install using software centre But it wasn't installing without giving any error logs. Then I opened it with Gdebi installer. Here is what I saw.    I have already trying enabling multiverse repositories.  Edit: I have downloaded the amd64 package from the WPS official site, but even now installing through terminal I still get the missing dependencies error. Why are loops always compiled into "do...while" style (tail jump)? Dollar cost averaging - Should I still do it if I have a large pile of cash now? I currently have a large pile of cash savings ($240,000) which I really should have been investing all this time, but the past is past and no point dwelling on it.  I am currently 38 years old (2 kids. Wife who is also a high earner - $100,000), with a high salary ($150,000). I have read "The Intelligent Investor" and am really sold on dollar cost averaging as a strategy, using the index funds offered by Vanguard.  My current dilemma is what to do with the cash I already have. My current plan is to still follow the dollar cost averaging and slowly move it into vanguard over a period of 4 years (~$5000 per month). While leaving the remaining parts of the cash in term deposits. So $50,000 in a 3 year term deposit at 3%, $50,000 in a 2 year term deposit at 2.8% etc.  But in someways it feels overly conservative. Should I just move all the money now? Or perhaps in a shorter time frame (3 years? 2 years? 1 year?).  There are a few other questions on the site similar to mine, but they are from 2013/2014 etc. Given that currently the stock market is at a high and there is a lot of economic uncertainty on the horizon, putting everything in the stock/bond market at once now seems like a risky move. And it seems to violate the principle of dollar cost averaging. Or am I violating dollar cost averaging by trying to "time the market" by looking at it's current value?  Reading this section  seems to indicate that I should just invest everything now. But the first paragraph also seems to suggest giving more weight to that advice if the market was trending upwards (Which I am not certain the current market is/will be for long).  PS: My current investment horizon is long. Basically retirement, about 20 years from now. Simple examples of uncorrelated but not independent $X$ and $Y$ Any hard-working student is a counterexample to "all students are lazy".  What are some simple counterexamples to "if random variables $X$ and $Y$ are uncorrelated then they are independent"? How does HOTP keep in sync? My understanding of  is that each password is unique and based on a counter.    $$PASSWORD = HOTP_1(K,C)$$  Where $C$ is an incremental counter.  What I wish to know, is how you keep the client and server in sync?  Looking at current systems (google authenticator), there appears to be no indication if the actual 'counter' number, but you can generate successive passwords at will.  What happens if, for example, the password you have generated uses $C = 5$, but the server is expecting $C = 3$?  Also, what is the 'integrity check' for?  Google cant seem to come up with a solution. By conservation of energy, the solid is left in a lower energy state following emission of a photon.  Clearly absorption and emission balance at thermal equilibrium, however, thermodynamic equilibrium is a statement of the mean behaviour of the system, not a statement that the internal energy is constant on arbitrarily short timescales.  The energy has to come from somewhere during emission, and go somewhere during absorption.  Energy in a solid can be stored as kinetic and potential energy of electrons and nuclei, either individually or in collective modes such as phonons and plasmons.  In thermal equilibrium energy will be stored more or less in various forms depending on the temperature and material.  However, even if most of the thermal energy in a particular solid at temperature $T$ is stored in the form of phonons, it could be that phonons primarily interact with light indirectly via electrons, e.g. a phonon excites an electron in a phonon-electron interaction, which can interact with light via the EM field.  Given that light is an EM field, it makes sense to me that it is emitted and absorbed by charged particles.  The electron-photon interaction is probably dominant for visible and ultraviolet light, given that metals are opaque, while semiconductors and insulators are transparent to (visible and UV) light with energy lower than their bandgap. However, once you get into energies in the IR and below, or X-rays and above, other mechanisms apparently take over.  For example, on the high-energy end of the spectrum I've heard that gamma rays can interact directly with nuclear degrees of freedom, which is reasonable considering that gamma rays are emitted during a lot of nuclear reactions.  A review of  might give clues to important light-matter interactions over a broad range of wavelengths.  Whether all of the these processes are involved in blackbody emission is a somewhat different question.  What physical processes mediate energy transfer during blackbody emission, and in which energy ranges are the various processes dominant? Is there a dominant gene for right-handedness? Has there been any definitive research about handedness being genetic? Also, why is right-handedness clearly dominant in humans? I'm interested in evolutionary theories, as well as any molecular explanation (if known). How to solve a difference equation? So I have the difference equation $4y_{k+1} = 2y_k$.  I need to solve this equation, first with the initial condition $y_0 = 0$ and then with the initial condition $y_0 = 2$.  The professor wrote on the answer sheet that applying iteratively the recurrence relation it is easy to check that:  $y_k= (1/2)^k y_0 $.  Since I missed the lecture where he explained this, can somebody explain how to come about with this question?  I imagine that once I get the equation, then the initial condition $y_0 = 0$ gives us the particular solution $y_k = 0$. Thus the other initial condition $y_0 = 2$ is verified by the solution $y_k = 2(1/2)^k$.  Any help on how to get to the equation $y_k= (1/2)^k y_0$ will be appreciated. What content type to force download of text response? I need to stream a file to the Response for saving on the end user's machine.  The file is plain text, so what content type can I use to prevent the text being displayed in the browser? The dissolve tool (vector>geoprocessing tools>dissolve) renders some artifacts on shapes with high number of polygons. I’m using a  with 3222 polygons and I’m trying to dissolve it using the field “municipio”, but when the dissolve tool ends calculating the new shape has some artifacts     Does anyone had a similar problem? How to work around it?  I’ve also used v.dissolve from GRASS and the dissolve polygon from SAGA, but the problem persists. I’ve used the same shapefile on ArcGIS 9.3 with the dissolve tool. None artifact/error was produced.  Edit 1  I'm trying to use the v.clean tool as sugested by WhiteboxDev. However I'm getting this error:     An error has occured while executing Python code:      Traceback (most recent call last):   File   "C:/PROGRA~1/QGISCH~1/apps/qgis/./python/plugins\processing\gui\ProcessingToolbox.py",   line 181, in executeAlgorithm   File   "C:/PROGRA~1/QGISCH~1/apps/qgis/./python/plugins\processing\algs\grass7\Grass7Algorithm.py",   line 511, in checkBeforeOpeningParametersDialog   File   "C:/PROGRA~1/QGISCH~1/apps/qgis/./python/plugins\processing\algs\grass7\Grass7Utils.py",   line 361, in checkGrass7IsInstalled   File   "C:\PROGRA~1\QGISCH~1\apps\Python27\lib\ntpath.py", line 96, in join   TypeError: object of type 'NoneType' has no len()      Python version:   2.7.4 (default, Apr  6 2013, 19:54:46) [MSC v.1500 32 bit (Intel)]      QGIS version:   2.4.0-Chugiak Chugiak, 8fdd08a      Python path:   ['C:/PROGRA~1/QGISCH~1/apps/qgis/./python/plugins\processing',   'C:/PROGRA~1/QGISCH~1/apps/qgis/./python',   u'C:/Users/CERCOTRICHAS/.qgis2/python',   u'C:/Users/CERCOTRICHAS/.qgis2/python/plugins',   'C:/PROGRA~1/QGISCH~1/apps/qgis/./python/plugins',   'C:\PROGRA~1\QGISCH~1\bin\python27.zip',   'C:\PROGRA~1\QGISCH~1\apps\Python27\DLLs',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\plat-win',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\lib-tk',   'C:\PROGRA~1\QGISCH~1\bin',   'C:\PROGRA~1\QGISCH~1\apps\Python27',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\GDAL-1.11.0-py2.7-win32.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\PIL',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\jinja2-2.7.2-py2.7.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\markupsafe-0.23-py2.7-win32.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\python_dateutil-2.2-py2.7.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\pytz-2014.2-py2.7.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\win32',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\win32\lib',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\Pythonwin',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\Shapely-1.2.18-py2.7-win32.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\six-1.6.1-py2.7.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\wx-2.8-msw-unicode',   'C:\PROGRA~1\QGISCH~1\apps\qgis\python\plugins\fTools\tools',   'C:\Program Files\SpiderOak\shell_extension_lib\shared.zip']   Not entirely sure if this error is QGIS related... Any idea why I'm getting this error and how can I solve it? Is there some way to get explorer to generate thumbnails without actually having to navigate and scroll through every folder?  All I could get was a command prompt script that would load an explorer window for all subfolders, however only images that were visible would have thumbnails created.