calculator with linkedlist java
How do I compare strings in Java?
Making a live USB with persistent storage I need to simulate the warning:  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!  @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@  IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!   I have two Linux machines and when I do ssh from Linux1 to Linux2, ssh accepted and reports no problem.  But because some of testing, I want to simulate the - Identification Has Changed error  So what I need to edit on the remote server in order to create the problem?  what I did until now is to change the knpwn_hosts on both machine but its not creating the problem.  I get this:   key_read: uudecode AAAAB3NzaC1y3jrzG62xyHrb3qxc9eYpg1Cp1PrRElTFfYbEHsRfTZU21S8kO5/Tq+ED8=  failed  key_read: uudecode AAAAB3NzaC1y3jrzG62xyHrb3qxc9eYpg1Cp1PrRElTFfYbEHsRfTZU21S8kO5/Tq+ED8=  failed  The authenticity of host 'ste1 (10.106.164.111)' can't be established.  RSA key fingerprint is 84:82:2b:80:ca:3f:57:c7:8c:14:44:dd:b9:70:e5:d8.  Are you sure you want to continue connecting (yes/no)? A file manager with free icon placing option Prove that vector space and dual space have same dimension As an exercise in my textbook, I need to prove that if $V$ is a finite dimensional vector space with dual space $V^*$ over $\mathbb{R}$, then dim$(V)$=dim$(V^*)$.  Let $\omega\in V^*$ and let $\{e_1,...,e_n\}$ be a basis for $V$. Define $e^i\in V^*$ by $e^i(e_j)=\delta_{ij}$. We show that $\{e^1,...,e^n\}$ spans $V^*$. $\omega(v)=\omega(v_1e_1+...+v_ne_n)=v_1\omega(e_1)+...+v_n\omega(e_n).$ If $\omega(e_1)=\lambda_1,...,\omega(e_n)=\lambda_n$, then $\omega(v)=v_1\lambda_1e^1(e_1)+...+v_n\lambda_ne^n(e_n)$=$\lambda_1e^1(v)+...+\lambda_ne^n(v)$.   To show $\{e^1,...,e^n\}$ is linearly independent, suppose that $0=c_1e^1+...+c_ne^n$ is the zero mapping to $\mathbb{R}$. Consider the image of $e_1:$  $0(e_1)=c_1*1+...+c_n*0=c_1$ Hence, $c_1=0$. Repeating the procedure for $e_j$, $2\leq j\leq n$, we see that $c_1=c_2=...=c_n=0$.  Does this proof look correct?  If the proof is correct, I have an additional small question. It seems like this proof is dependent on the fact that $V$ is a real (or complex) vector space, since we define the covectors to have the image set $\{0,1\}$. Is there a proof that works for vectors spaces over general fields? Are there massless bosons at scales above electroweak scale? Spontaneous electroweak symmetry breaking (i.e. $SU(2)\times U(1)\to U(1)_{em}$ ) is at scale about 100 Gev. So, for , gauge bosons $Z$ &amp; $W$ have masses about 100 GeV. But before this spontaneous symmetry breaking ( i.e. Energy > 100 GeV) the symmetry $SU(2)\times U(1)$ is not broken, and therefore gauge bosons are massless.  The same thing happens when we go around energy about $10^{16}$ GeV, where we have the Grand Unification between electroweak and strong interactions, in some bigger group ($SU(5)$, $SO(10)$ or others). So theoretically we should find gauge bosons $X$ and $Y$ with masses about $10^{16}$ GeV after GUT symmetry breaks into the Standard Model gauge group $SU(3)\times SU(2)\times U(1)$, and we should find massless X and Y bosons at bigger energies (where GUT isn't broken).  So this is what happened in the early universe: when temperature decreased, spontaneous symmetry breaking happened and firstly $X$ &amp; $Y$ gauge bosons obtained mass and finally $Z$ &amp; $W$ bosons obtained mass.   Now, I ask: have I understood this correctly? In other words, if we make experiments at energy above the electroweak scale (100 GeV) we are where $SU(2)\times U(1)$ isn't broken and then we should (experimentally) find $SU(2)$ and $U(1)$ massless gauge bosons, i.e. $W^1$, $W^2$, $W^3$ and $B$ with zero mass? But this is strange, because if I remember well in LHC we have just make experiments at energy about 1 TeV, but we haven't discovered any massless gauge bosons. How to write permutations as product of disjoint cycles and transpositions $$\sigma=\begin{pmatrix} 1 &amp; 2 &amp;3 &amp; 4&amp; 5&amp; 6&amp;7 &amp;8 &amp;9 &amp;10 &amp; 11 \\ 4&amp;2&amp;9&amp;10&amp;6&amp;5&amp;11&amp;7&amp;8&amp;1&amp;3    \end{pmatrix}$$  (1) I am asked to write this permutation in $S_{11}$ as a product of disjoint cycles and also as a product of transpositions.   (2) Also find the order of the element. Is this permutation even or odd?  I think these are the disjoint cycles  $E_{1}=(1,4,10)$, $\;\operatorname{order}E_1 =3$  $E_{2}= (3,9,8,7,11),\;$ $\operatorname{order}E_{2} =5$  $E_{3}=(5,6),\;$ $\operatorname{order}E_{3} =2$  $S_{11}$=  $E_{1} \cdot E_{2}\cdot  E_{3}$  The order of $\operatorname{order}E_{3}$ is even so the order of the permutation is even. Why are they asking this? And what is the significance of it being even or odd?  Transpositions – I have read this a couple times but the one example in my textbook is rather unclear, I am not sure what this means?  I think the transposition for $E_{1}$ is $(1,4)(1,10)$ but I'm not sure what this means. My system is not dual-boot, I run a standard Ubuntu desktop system "on the metal" (I think running it in a VM is the same).  Pressing c while booting does not cause the GRUB menu to appear (which I believe it does for a dual-boot system).  How can I get the GRUB-menu to present itself on a single-boot system? Why is $1$ not a prime number? Why is $1$ not considered a prime number?  Or, why is the definition of prime numbers given for integers greater than $1$? (p.236)  has a proof that the equation $e^z-z=0$ has infinitely many complex solutions:    I'm curious if there are any particularly elegant ways to see this, other than that given in the text. I cant change to faces or edges view! If an polynomial has a complex root, is it necessary that the conjugate of that root is also a root of the polynomial? I am not sure about this. Please comment on this. Best technique to create oldschool (fake 3D) racing game? What would be a good approach to develop the render system for an oldschool type racing game that uses a pseudo 3D scenery, like for example Outrun or Lotus Esprit Turbo Challenge? There's an endless scrolling road and scenery graphics are placed like billboard items, etc. I think you get the idea.    Are these developed in a similar way like  or is there a different technique behind it? Does the technique has a specific name I could search for on the web? I need to develop something like that in Flash. Application of Kolmogorov's Zero-One Law Most of the books I read, they only state some examples of tail events. One of them is  $[\sum_n X_n \ converges]$. My main problem is to show that this is indeed a tail event. How does the pull down resistor work in this circuit? How to get rid of OTA software update notification? I upgraded my Nexus 4 to Lollipop a few days ago but I don't like it. I'll leave out my reasons because they're not relevant here. I wiped my phone and installed a clean stock 4.2.2 version instead. I'm happy with this.  Not long after, Android automatically downloaded the 4.3 upgrade and notifies me with the choices "Later" and "Install". I don't want to do this upgrade.  How do I:   get rid of the notification, and  remove the downloaded update (to free up precious storage space).     I have already tried choosing "Later" but the same notification immediately reappears.    Based on Google search results, I also tried going to Settings &gt; Apps &gt; All &gt; Google Services Framework and unticked "show notifications" but it still appears. Force stop or disable also doesn't seem to help, so I've re-enabled the service including notifications. I didn't see any other apps in this list that sounded relevant - did I just not see it? I'm trying to setup OpenVPN using NetworkManager. The GUI seems buggy and unresponsive. Are there any other tools for setting up a VPN client? Open local folder from link PHP script not executing on Apache server Induced metric on a null hypersurface Generic Parse Method without Boxing I am trying to write a generic Parse method that converts and returns a strongly typed value from a NamedValueCollection.  I tried two methods but both of these methods are going through boxing and unboxing to get the value.  Does anyone know a way to avoid the boxing?  If you saw this in production would you not like it, how bad is it for performance?  Usuage:  var id = Request.QueryString.Parse&lt;int&gt;("id");   Attempt #1:  public static T Parse&lt;T&gt;(this NameValueCollection col, string key) {     string value = col[key];      if (string.IsNullOrEmpty(value))         return default(T);      if (typeof(T) == typeof(int))     {         //return int.Parse(value); // cannot convert int to T         //return (T)int.Parse(value); // cannot convert int to T         return (T)(object)int.Parse(value); // works but boxes     }     if (typeof(T) == typeof(long))     {         return (T)(object)long.Parse(value); // works but boxes     }     ...      return default(T); }   Attempt #2 (using reflection):  public static T Parse&lt;T&gt;(this NameValueCollection col, string key) {     string value = col[key];      if (string.IsNullOrEmpty(value))         return default(T);      try     {         var parseMethod = typeof(T).GetMethod("Parse", new Type[] { typeof(string) });          if (parseMethod == null)             return default(T);          // still boxing because invoke returns an object         var parsedVal = parseMethod.Invoke(null, new object[] { value });         return (T)parsedVal;     }     // No Proper Parse Method found     catch(AmbiguousMatchException)      {     }      return default(T); }