A matrix with integers entries and complex solution.
Prove or Disprove the Existence of Solutions...
How do I get a Realtek RTL8723BE wireless card to work? I have installed Ubuntu 15.04 on my laptop with RTL8723BE Wi-fi card. But it is always disconnecting from network. I have tried echo "options rtl8723be fwlps=N ips=N" | sudo tee /etc/modprobe.d/rtl8723be.conf but that didn't helped. What can I do to prevent the wifi from disconnecting? If I upgrade to kernel 4.X, will it help?  ~$ lspci -knn | grep Net -A2  09:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. RTL8723BE PCIe Wireless Network Adapter [10ec:b723]     Subsystem: Hewlett-Packard Company Device [103c:2231]     Kernel driver in use: rtl8723be   ~$ rfkill list 0: hci0: Bluetooth     Soft blocked: yes     Hard blocked: no 1: phy0: Wireless LAN     Soft blocked: no     Hard blocked: no   ~$ ifconfig &amp;&amp; iwconfig &amp;&amp; route -n &amp;&amp; ping -c 1 google.com eth0      Link encap:Ethernet  HWaddr 38:63:bb:cd:4a:7e             UP BROADCAST MULTICAST  MTU:1500  Metric:1           RX packets:3 errors:0 dropped:0 overruns:0 frame:0           TX packets:53 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:1000            RX bytes:752 (752.0 B)  TX bytes:8445 (8.4 KB)  lo        Link encap:Local Loopback             inet addr:127.0.0.1  Mask:255.0.0.0           inet6 addr: ::1/128 Scope:Host           UP LOOPBACK RUNNING  MTU:65536  Metric:1           RX packets:3870 errors:0 dropped:0 overruns:0 frame:0           TX packets:3870 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:0            RX bytes:314613 (314.6 KB)  TX bytes:314613 (314.6 KB)  wlan0     Link encap:Ethernet  HWaddr c0:38:96:6d:c4:83             inet addr:192.168.1.205  Bcast:192.168.1.255  Mask:255.255.255.0           inet6 addr: fe80::c238:96ff:fe6d:c483/64 Scope:Link           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1           RX packets:15240 errors:0 dropped:0 overruns:0 frame:0           TX packets:14627 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:1000            RX bytes:14410285 (14.4 MB)  TX bytes:2192744 (2.1 MB)  eth0      no wireless extensions.  wlan0     IEEE 802.11bgn  ESSID:"DIR-615"             Mode:Managed  Frequency:2.437 GHz  Access Point: 00:90:4C:08:00:0D              Bit Rate=150 Mb/s   Tx-Power=20 dBm              Retry short limit:7   RTS thr=2347 B   Fragment thr:off           Power Management:off           Link Quality=70/70  Signal level=-22 dBm             Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0           Tx excessive retries:0  Invalid misc:186   Missed beacon:0  lo        no wireless extensions.  Kernel IP routing table Destination     Gateway         Genmask         Flags Metric Ref    Use Iface 0.0.0.0         192.168.1.1     0.0.0.0         UG    400    0        0 wlan0 169.254.0.0     0.0.0.0         255.255.0.0     U     1000   0        0 wlan0 192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 wlan0 PING google.com.Dlink (172.26.136.19) 56(84) bytes of data. 64 bytes from 19.136.26.172.in-addr.arpa (172.26.136.19): icmp_seq=1 ttl=249 time=102 ms  --- google.com.Dlink ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 102.547/102.547/102.547/0.000 ms Why are random walks intercorrelated? Prove that $\mathbb{Z}$ is not isomorphic to additive group of any vector space over any field.  Proof.  Surpose that: $\phi : (A, +) \rightarrow  \mathbb{Z} $ is an isomorphism. Then there is some $r∈A $ such that $ϕ(r)=1_\mathbb{Z}$. We have $$ 1_\mathbb{Z}=ϕ(r)=ϕ(2(r/2))=2ϕ(r/2)$$  or equivalently that $ϕ(r/2)=\frac{1}{2}$. But this is not in $ \mathbb{Z}$, so there can be no such morphism.  Is my proof above correct? Thanks Why is CBS.log file size 20 GB Google Chrome: Import/Export Passwords? I recently migrated from Windows7 to Kubuntu 10.0.4. In many ways, I'm loving the change. (I never knew it could be such a seemless process to write/test scripts!)  One of the few things that is causing me any hangup is that none of the passwords that were saved in my browser are available (obviously, since it's a completely separate installation). Is it possible to export my passwords from the Windows instance of Chrome and then import them into the Linux version? Word for "scary thing that's about to occur"? I have the feeling I'm forgetting a very simple word. But anyway, is there a word for that? Example:     The [...] that haven't occurred yet are the most scary ones. Can you cast a 9th level spell if your multiclass spell slots have 9th level spell slots? How to get a list of appendices? How to get a list of appendices like the list of figures and list of tables? How to set it on a separate page, like the list of figures and list of tables? Dictionary definitions  often seem to use the terms sentience, awareness, and consciousness as if they are synonymous with each other. Is this really the case? If not, how do they differ? Some books suggest that sentience and awareness are simply facets of the larger concept of consciousness. My book uses the argument that the multiplicities of a few macrostates in a macroscopic object take up an extraordinarily large share of all possible microstates, such that even over the entire lifetime of the universe, if each microstate had an equal chance of being accessed, fluctuations away from equilibrium would never occur.  My question to this statistical proof is this: In the real world, is there really an infinitesimal but nonzero chance that macroscopic systems could access some of the more unlikely macrostates (e.g. heat transfer from a cold object to a hot object)? I have a sprite sheet from a classic video game (if you're curious, Final Fight) that I'd like to be broken up into indivual images to be used in . However, the images aren't on an even grid, and all have a different amount of space between them.  Is there an automated way to export images based on contiguous pixels or something like that? Variable scoping in Module Supersymmetry in Quantum Field Theory I have an idea of supersymmetry in quantum mechanics, can you suggest a book on "supersymmetry in quantum field theory", which has sufficient mathematical rigour like "Peskin and Schroeder" Can a Filipino citizen with no Korean visa with a long layover in Seoul take the airport free city tour? I am a Filipino citizen traveling from Saipan to Manila via Seoul, with 13 hours layover.  Do I need a Korean visa to take the airport free city tour? Do you have to want to hurt someone for the cruciatus curse to work? If I am shooting the 8-ball for a win, and my opponent has a ball near the pocket I'm aiming for, can I call something like "8-ball off the 2 ball into the corner pocket"?  I thought this was allowed, but a friend says this is an automatic loss and that the 8-ball must never touch another ball before going into the pocket.  Various pool rules aren't clear for me on this scenario. Why do adult insects have 6 legs? Apparently, there is an advantage to having 6 legs in the insect world. What is that advantage, if anything? Why would such an advantage exist for insects, but not for other, larger land animals?  What do those middle legs do that the front and hind legs cannot, if anything? Are they really essential, or do they just generate more muscle power? Should my canonical URLs have only the ID with no slug so that they don't change? Our URLs will be created by the user's content.  Eg:  www.example.com/bar-1234/i-went-to-baz-4321  The "i went to baz" portion is user generated, included with the aim of being helpful to the person viewing the URL and also to possibly contain useful keywords for search engines.  However, the string that forms that portion is user editable. So it could become:  www.example.com/bar-1234/we-drove-to-baz-4321  AFAICT the canonical URL should be:  www.example.com/bar-1234/4321  The string portion is discarded by the controller, which means that there's potential for duplicate content from limitless URLs!  So, my question is, does it matter if my canonical URL is 'non SEO friendly'?  It seems logical to me to provide search engines with the "id only" version of the URL which is always consistent, but the canonical URL is the one that appears in search results, so is there any benefit from trying to use more 'SEO friendly' URLs? Moderators should not close crap, flamebait questions, let the community When a moderator comes across a question that deserves to be closed, they should not. This should be left to the community to handle.   Here's a fresh example right out of the Stack Overflow oven: "".   It's a crappy question, to be sure.  It is long, ranty, and flame-fodder.  It should have been closed, but not by a moderator.  It is not the moderators' jobs to decide on their own what is and is not proper content for a site.  That is the job of the community. I want to uninstall VMware Player on my Ubuntu 12.04 LTS system. How should I uninstall it?