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How can I convert from hex to base64? Can anyone recommend a straightforward way/tool to convert hex to base64?  I'm using Linux and OS X. VMware won't work after Ubuntu Upgrade I upgraded to Ubuntu 15.10 and now if I want to open VMware Player it doesn't do anything. I also uninstalled and installed it again, still nothing.  What can I do? A well-known application of the MVT is to prove that any $f: \mathbb{R} \to \mathbb{R}$ with $f'= 0$ is constant. But of course, the MVT relies fundamentally on the properties of $\mathbb{R}$, and in particular does not hold in $\mathbb{Q}$. A standard counter-example is the function $f :\mathbb{Q} \to \mathbb{Q}$ defined by $ f(x)=0 $ if $ x &lt;\sqrt{2}$, and $f(x)=1$ if $ x &gt; \sqrt{2}$, for this function is locally constant. There are several ways of thinking about the difference between $\mathbb{R}$ and $\mathbb{Q}$ : $\mathbb{R}$ is connected while $\mathbb{Q}$ is totally disconnected, closed bounded intervals are compact in $\mathbb{R}$, but not in $\mathbb{Q}$, $\mathbb{R}$ satisfies the least upper bound axiom, $\mathbb{Q}$ does not.   Now, I wanted to see how far one could push this counterexample - is there a function $f :\mathbb{Q} \to \mathbb{Q}$ such that $f'=0$ and $f$ is strictly increasing? Clearly, any slight modification of the usual counterexample where $f$ is locally constant will not do. Also, one can show that if $f$ is uniformly differentiable with derivative zero, it must be constant, even in $\mathbb{Q}$, so I knew I was looking for non-uniformly differentiable but still differentiable $f$.   Eventually, I came up with a construction, albeit not a very explicit one: the idea is that, since $\mathbb{Q}$ is countable, one can enumerate it $q_{1}, q_{2}, q_{3}, \cdots$, and then define $f: \mathbb{Q} \to \mathbb{Q}$ inductively and recursively. If one could define $f$ in such a way that $ \forall \ q_{n} \in \mathbb{Q} \ \exists \ c_{n} \in \mathbb{Q} : \forall \ x \in \mathbb{Q} \ |f(x)-f(q_{n})| \leq c_{n}|x-q_{n}|^2$, and $f$ is strictly increasing, we would be done. The recursive definition essentially defines $f(q_{n+1})$, after having defined $f(q_{1}),f(q_{2}),f(q_{3}), \cdots , f(q_{n})$, in such a way that these inequalities hold and $f$ is strictly increasing, and at each step the new $c_{n}$ is chosen large enough so that these inequalities do not become incompatible at subsequent steps ( I am willing to provide more details of this construction if asked).  Note that, as $n \to \infty$, we must have $c_{n} \to \infty$, so that $f$ is not uniformly differentiable. Interestingly, the only key fact about $\mathbb{Q}$ used in the construction is that it is countable, so in a sense the construction provides a proof that $\mathbb{R}$ is uncountable, given the MVT.  While the construction works, it is not very simple nor explicit, which is perhaps to be expected, and the function must be evaluated point by point in the order given by the enumeration of $\mathbb{Q}$. So I was wondering if anyone else knows or can come up with a simpler construction of a function $ f : \mathbb{Q} \to \mathbb{Q}$ such that $f'=0$ and $f$ is strictly increasing. Any thoughts and ideas are welcome.  Edit: I've asked the same question on MO: What GUI applications are there to assist in generating graphics for TeX? For which $n$ is the sum: $$\sum_{k=0}^{n}10^k$$ a prime number? Are they finite? I have an HP ProBook 450 G2. Every time I shut down the computer and turn it back on after a day, the battery level decreases by about 5%. I'm sure that the computer is shut down, not in sleep or hibernate. I removed the battery from laptop and after inserting it, the battery percentage does not change. I tried updating the BIOS, disabling wake on LAN in BIOS options, and calibrating the battery several times.  Is this drain normal? If not, is it a hardware failure or can I fix it with software? Question of an isomorphism of $\epsilon_ 0$ and a subset of the rationals. How do the likely/unlikely macros in the Linux kernel work and what is their benefit? What is the best way to open a file for exclusive access in Python? What is the most elegant way to solve this:   open a file for reading, but only if it is not already opened for writing open a file for writing, but only if it is not already opened for reading or writing   The built-in functions work like this  &gt;&gt;&gt; path = r"c:\scr.txt" &gt;&gt;&gt; file1 = open(path, "w") &gt;&gt;&gt; print file1 &lt;open file 'c:\scr.txt', mode 'w' at 0x019F88D8&gt; &gt;&gt;&gt; file2 = open(path, "w") &gt;&gt;&gt; print file2 &lt;open file 'c:\scr.txt', mode 'w' at 0x02332188&gt; &gt;&gt;&gt; file1.write("111") &gt;&gt;&gt; file2.write("222") &gt;&gt;&gt; file1.close()   scr.txt now contains '111'.  &gt;&gt;&gt; file2.close()   scr.txt was overwritten and now contains '222' (on Windows, Python 2.4).  The solution should work inside the same process (like in the example above) as well as when another process has opened the file. It is preferred, if a crashing program will not keep the lock open. What is the geometric interpretation of the transpose? Remove the extra headers from the e-mails sent Word to describe someone who publishes many works? What word describes an author who publishes many works?  "Profuse" comes to mind, but this word has a broader meaning. My DOM looks like this:  &lt;div id="d1"&gt;    &lt;div class="c1"&gt;             &lt;a href="#"&gt;&lt;img src="img1_on.gif"&gt;&lt;/a&gt;             &lt;a href="#"&gt;&lt;img src="img2_on.gif"&gt;&lt;/a&gt;    &lt;/div&gt; &lt;/div&gt;   When someone clicks on an image, I want the image src to change to &lt;img src="imgx_off.gif"&gt; where x represents the image number 1 or 2.  Is this possible or do I have to use CSS to change the images? Reading a 5 Band resistor with Gold as a middle band? Can anyone read the resistor that the arrow is pointing to?  From what I know you can not have a gold band as a number and if I am reading it correctly it has a tolerance of 0 which does not seem right. My site has 30,000 visits with 86,000 page views. If the bounce rate of 54%, then does it means only 15,000 users generated the 86,000 page views or 30,000 visits generated the 86,000 page views.  My website is www.cricandcric.com  Even though I have got 86,000 page views, my site's Alexa ranking is still getting worse day by day. How do I control that? Let's say I'm trying to answer a lot of questions just to up my reputation (even if I generally don't know what I'm talking about).  Then, whenever I get downvoted, I just delete my answer so that nobody sees that I've posted stupid answers, and so I don't lose reputation points.   Is this frowned upon? Do I lose reputation points on downvoted answers if I delete them? How to do joins in LINQ on multiple fields in single join I need to do a LINQ2DataSet query that does a join on more than one field (as  var result = from x in entity join y in entity2         on x.field1 = y.field1  and            x.field2 = y.field2   I have yet found a suitable solution (I can add the extra constraints to a where clause, but this is far from a suitable solution, or use  solution, but that assumes an equijoin).  Is it possible in LINQ to join on multiple fields in a single join?  EDIT  var result = from x in entity              join y in entity2              on new { x.field1, x.field2 } equals new { y.field1, y.field2 }   is the solution I referenced as assuming an equijoin above.  Further EDIT  To answer criticism that my original example was an equijoin, I do acknowledge that, My current requirement is for an equijoin and I have already employed the solution I referenced above.  I am, however, trying to understand what possibilities and best practices I have / should employ with LINQ. I am going to need to do a Date range query join with a table ID soon, and was just pre-empting that issue, It looks like I shall have to add the date range in the where clause.  Thanks, as always, for all suggestions and comments given If $[\cdot]$ denotes greatest integer function, then what is the value of natural number $n$ satisfying the equation $$[\log_21]+[\log_22]+[\log_23]+\dots[\log_2n]=1538 ?$$   My try:  Note that  $$0+1\times2+2\times2^2+3\times2^3+4\times2^4+5\times2^5+6\times2^6+7\times2^7=1538$$  But the answer is $$n=\sum_{i=0}^72^i=255.$$  How is it derived? Why does inductor current lag the applied voltage at its terminal by 90 degrees? I studied electromagnetism and I am currently working with Inductors.  I could not figure out the physical reason based on electromagnetics on why inductor current lags the applied voltage by 90 degrees?  Everywhere I find the Formula as the starting point of explanation which is partially satisfying.    Induced EMF =L di(t)/dt    From the above equation, I understood that when there is a change in current there will EMF induced in the coil terminals. But How this induced EMF makes the current to lag the supply voltage V(t) = Vm*sin(wt)? (Please don't just differentiate and say there is a lag, I am looking for a physical sense on why this happens)  Lets us consider the AC voltage is applied across the terminal at time t=0; At this time there is almost no current. From this transient state how the steady-state is reached where the current is delayed with respect to the voltage?  Can someone help me to figure out why the current lags the Supplied voltage by using electromagnetism, the motion of Charges or any other basic concepts? Motor to spin slowly, low torque