Can't plot derivative of Hankel function
General::ivar is not a valid variable when plotting - what actually causes this and how to avoid it?
In ZFC, a good way of ordering sets by cardinality is by leveraging the notion of an injection. We define: $$X \lesssim Y \leftrightarrow \mbox{ there exists an injection } X \rightarrow Y.$$  Alternatively, we can leverage the notion of a partial surjection, by which I mean a partial function that hits every point of its codomain at least once.  $$Y \succsim X \leftrightarrow \mbox{ there exists a partial surjection } Y \rightarrow X.$$  Now in ZFC, these approaches are equivalent, in the sense that $$X \lesssim Y \iff Y \succsim X.$$  But if we just consider ZF (that is, we drop choice) then the equivalence breaks down. However, we've still got the forward implication, because the converse of an injection is always a partial surjection.  A specific question. Define that two sets are weakly equipotent iff $X \succsim Y$ and $Y \succsim X$. Question: does weak equipotence imply genuine equipotence? I'm guessing "no."  A general question: In broad terms, how would the structure of the cardinal numbers in ZF be altered by adopting $\succsim$ rather than $\lesssim$ as the fundamental order relation, and taking equality of cardinal numbers to correspond to weak equipotence of sets? I'm guessing this would hide a lot of the (usually very complicated) structure of the cardinal numbers in ZF.  Remark. The order symbols can be written \lesssim and \succsim. "Open With" dialog ignores my selection I am running Windows 7 x64. I have a file type that I want to associate with Microsoft Access 2003.  I right-click on the file and select Open With->Choose Default program. In the "Open With" dialog, I select the browse button. I choose Program Files (x86)\Microsoft Office\Office11\msaccess.exe and press "Open".  I end up back at the "Open With" dialog, but nothing has changed. Access is not listed as a program to use to open the file with. The original program (Adobe Acrobat) that is associated with this program is still selected.  Any tips on getting this association to work? What kind of construct is 'would that that were all'? There is a place in Bram Stoker’s Dracula where I can’t quite parse the grammar:     8 May. — I began to fear as I wrote in this book that I was getting too   diffuse. But now I am glad that I went into detail from the first, for   there is something so strange about this place and all in it that I cannot   but feel uneasy. I wish I were safe out of it, or that I had never come. It   may be that this strange night existence is telling on me, but would that   that were all!   I understand the meaning of the text in bold (it’s equivalent to if only that was all!), but I don’t understand the grammar being used. What kind of construct is this? Is soaking beans 24 hours unrefrigerated safe? It strikes me as an unsafe food practice to follow Cook's Illustrated's advice for soaking dried beans for 24 hours unrefrigerated.  I've also seen them suggest you soak steel-cut oats unrefrigerated overnight.    Is there some reason why these practices are okay?  Would there be any harm in refrigerating them, particularly the beans, while soaking?  From Cook's Illustrated:     Dissolve 3 tablespoons salt in 4 quarts cold water in large bowl or   container. Add [one pound] beans and soak at room temperature for at least 8 hours   and up to 24 hours. Drain and rinse well. I have the following file:  abcde kwakwa &lt;0x1A&gt; line3 linllll   Where &lt;0x1A&gt; represents a byte with the hex value of 0x1A. When attempting to read this file in Python as:  for line in open('t.txt'):     print line,   It only reads the first two lines, and exits the loop.  The solution seems to be to open the file in binary (or universal newline mode) - 'rb' or 'rU'. Can you explain this behavior ? How do we prove that  $\operatorname{rank}(A) = \operatorname{rank}(AA^T) = \operatorname{rank}(A^TA)$ ?  Is it always true? A secant inequality for convex functions Can Mjolnir be lifted & wielded by anyone if Thor is touching it? In The Big Bang Theory episode , Penny, Amy, and Bernadette are having an argument if Thor's hammer:   Can be lifted by anyone in space.     Can be lifted &amp; wielded by anyone if Thor is touching it.   The first argument is settled in .  But the second argument remains unsolved.  Can Thor's hammer be lifted &amp; wielded by anyone if Thor is touching it? I regularly find sites that copy content from elsewhere (mailing lists, etc) while not providing any added value. Quite to the contrary, they are pretty heaped with ads.  I'd like to remove those sites as permanently as possible from my Google search results. Any ideas? Using Squeeze Theorem to show the following limits Consider a function f (x) defined on R satisfying:   for all x distinct 0.  Calculate: lim f(x) with x→∞ and limf(x) with x→−∞   Issue information:   if x → ∞ then we can consider | x | = x  if x → -∞ then we can consider | x | = -x  I can use x² = | x |? How do I get an iball 3.5G modem working on Ubuntu? I purchased iball 3.5G  connect wireless modem 1 month before. I am trying to connect it with my laptop which is having ubuntu Operating System. After plug-in it to the ubuntu system it is not connecting with net.   This modem is plug and play but after plugging it nothing is displaying to the system.  I am expecting step-by-step method to connect this modem with my ubuntu 12.04 LTS sysetm from your expert's advice. Set title for each terminal tab in gnome-terminal using a bash script I'm using Ubuntu 16.04  I want to open multiple terminal tabs, run commands and set title. I can open multiple tabs with this command:  gnome-terminal --tab -e "command1" --tab -e "command2"   but cannot use --title option as it is not available in this version.   I know mate-terminal can do this, but I want to use gnome-terminal.   I've applied solution posted  and it worked but when i run  gnome-terminal --tab -e "bash -c 'set-title 99;ping 192.168.7.99'"   It shows:  bash: set-title: command not found PING 192.168.7.99 (192.168.7.99) 56(84) bytes of data. 64 bytes from 192.168.7.99: icmp_seq=1 ttl=128 time=0.425 ms 64 bytes from 192.168.7.99: icmp_seq=2 ttl=128 time=0.353 ms 64 bytes from 192.168.7.99: icmp_seq=3 ttl=128 time=0.335 ms   I also applied   I've also read this post  but the accepted answer did not solve my issue in 16.04 os or gnome-terminal version 3.18.3 and other solution provides to use other terminal xterm and I want to use gnome-terminal. There a  who has no valid parent user. It is indicated that his chat account is associated to a Maths.SE account, which does not appear to exist. The user was still able to chat. Is it normal? If it's a bug, could someone look into it?  Edit: if you browse the Google cache for users named Skullpatrol, it turns out a single series of associated accounts. The user is now named . I don't know what went wrong, maybe an account merge or something like that, but it needs someone from staff looking into it with some superpowers. I also tried to update the parent user of the chat account to this &quot;Rob&quot; profile, but the interface goes all buggy on me (works for other users, fails only for this one): Permanent background ssh connection to create reverse tunnel: what is correct way? While reading a book, I came across the word I'd've, as in:     I'd've argued against it.   While it was obvious what it meant, it left me puzzled. Is I'd've a proper word? Can I use Bluray as a boot cd? Can there be two distinct, continuous functions that are equal at all rationals? Akhil showed that the  is the same as the continuum, using as a step the observation that continuous functions that agree at rational points must agree everywhere, since the rationals are dense in the reals.  This isn't an obvious step, so why is it true? No sound in Ubuntu except at log in I installed Ubuntu 12.04 a month ago and am using it till now. I failed to notice that all this time there was no sound at all while running Ubuntu, even while playing a game in Wine. The weird thing is that only the startup sound comes when I log in (Indian/African drum tone), then comes the utter silence.  I tested both Digital Output (S/PDIF) and the speakers in the sound settings but can hear nothing.  Any help? How can I recover from a "AMD-Action:downloadProduct:SP" during installation of macOS? Just wiped my hard drive on my MacBook Pro from 2013. Went to install a new copy of MacOS Sierra. I get the following error:  AMD-Action:downloadProduct:SP   I looked online and tried change the date using the Utility Terminal and the following command:  date mmddHHMMyy   Then did   csrutil enable csrutil clear   Then I tried clearing the NVRAM using command + option + P + R on startup.  Still no luck. Still getting the same error message. Apple support told me to go to a "computer repair store".  Any advice? Manually installing a program on Debian I have installed Debian on my pc, but the problem is that at the moment I have no Internet connection to this pc. So, to install a program I have to manually downloaded from a pc with internet and then install it to the linux-debian computer.  The question is this: Is there a standard way to make the installation manually? Note that when I connect a usb flash with the program I want to install(that is:   cdparanoia_3.10.2+debian-10.1_i386.deb) and I try opening it I get the message:     Failed to execute child process “ar” no file or directory.