I got an error of unexpected " in the code shown below  Tried to sum columns and then update each row in a SUM-Cell as I run the code.  $QQ = "UPDATE T_IMB19 SET SUM1=$SUMA, SUM2=$SUMB, TOTAL=$SUMTOT WHERE Navn=$rows['Navn']"; mysqli_query($con,$QQ);   I have echo on the SUMA, SUMB and SUMTOT and they act nicely, but the update doesn't work.     Error : "Parse error: syntax error, unexpected '' (T_ENCAPSED_AND_WHITESPACE), expecting identifier (T_STRING) or variable (T_VARIABLE) or number (T_NUM_STRING)"
If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?
Function $f(z)$ is holomorphic at least within the unit disk.   If for all arguments $|z|&lt;1$ we have $|f(z)| \le 1$, and there exists a zero of order $n$ at $z=z_0$, then show that $|f(0)| \le |z_0|^n$.  How should I tackle this problem? Can it be generalized if for $|z|&lt;R$ we have $|f(z)| \le M$ ?    So far I only understand that there exists a holomorphic $g(z)$ with $g(z_0) \ne 0$ such that $f(z) = (z-z_0)^n g(z)$,then $|f(z)| = |z-z_0|^n |g(z)| \le 1$ and moreover $|f(0)| = |z_0|^n |g(0)|$, but that doesn't seem useful since apparently I know too little about $g(z)$. In particular why should $|g(0)| \le 1$? If $M$ isn't Noetherian, $M$ has a submodule maximal with respect to being not finitely generated. I'm answering this question:     Let $M$  be a module. Show that if  $M$ is not Noetherian then $M$ has a submodule $N$ such that $N$ is not finitely generated but $A$ is finitely generated whenever $N &lt; A ≤ M$.   The solution starts as follows (I'm following a given solution): Let $Y$ be the set of non-finitely-generated submodules of $M$. If $(N_α)$ is a chain in $Y$ then $Q= \bigcup_αN_α $ is in $Y$, else $Q$ is f.g., which implies $Q=N_α$ for some $α$, whence $N_α$  is f.g., contradiction.  I don't understand why if $Q$ is f.g., then $Q=N_α$ for some $α$? Am I missing some fact?  Thanks! Splash Screen waiting until thread finishes I still have a problem with the splash screen. I don't want to use the property SC.TopMost=true.  Now my application scenario is as follows:  in progeram.cs:  [STAThread] static void Main() {     new SplashScreen(_tempAL);// where _tempAL is an arrayList     Application.Run(new Form1(_tempAL)); }   in SplashScreen class:  public SplashScreen(ArrayList _Data) {     DisplaySplash() }  private void DisplaySplash() {     this.Show();     this.TopMost = true;     this.CenterToScreen();     this.SetTopLevel(true);      _allServerNarrators = new string[10];     for (int i = 0; i &lt; _allServerNarrators.Length; i++)         _allServerNarrators[i] = null;      GetFromServer();      this.Hide();     _serverData = new ArrayList();     _thisData.Add(_allServerNarrators);     _thisData.Add(_serverNarrators);  } private void GetFromServer() {     _serverNarrators = new ArrayList();     string _file = "Suras.serverNar";      if (!Directory.Exists("c:\\ASGAQuraan"))         Directory.CreateDirectory("c:\\ASGAQuraan");      while (counter &lt; 4 &amp;&amp; _serverFiles == null)     {         if (Download("c:\\ASGAQuraan", _ftpServerIP, _file))         {             StreamReader _strReader = new StreamReader                          ("c:\\ASGAQuraan\\"+_file,System.Text.Encoding.Default);             string _line = _strReader.ReadLine();             string _word;              while (true)             {                 while (_line != null)                 {                     _word = _line.Substring(0, _line.IndexOf("*"));                     int _narId = Convert.ToInt32(_word);                     _line = _line.Substring(2);                     int k = 0;                     _serverNarratorNode = new ArrayList();                     while (true)                     {                         int ind = _line.IndexOf("*");                         if (ind &gt; 0 &amp;&amp; ind &lt; _line.Length)                         {                             string str = _line.Substring(0, (ind));                             if (k == 0)                             {                                 _allServerNarrators[_narId] = str;                                 _serverNarratorNode.Add(str);                             }                             else                             {                                 _serverNarratorNode.Add(str);                             }                             _line = _line.Substring(ind + 1);                             k++;                         }                         else                         {                             _line = null;                             break;                         }                     }                     _serverNarrators.Add(_serverNarratorNode);                     _serverFiles = "added";                 }                 _line = _strReader.ReadLine();                 if (_line == null)                 {                     break;                 }             }         }         else             counter++;     } }   What I want is something in the splash screen class which waits until the thread finishes.  For more details, please tell me what I need to tell you. how to create shortcode in wordpress So I have the following code:   &lt;span class="delete"&gt;&lt;a onclick="return confirm('Are you sure?');" href="&lt;?php echo wp_nonce_url( add_query_arg( array( 'action' =&gt; 'my-delete-product', 'product_id' =&gt; $post-&gt;ID ), my_get_navigation_url('products') ), 'my-delete-product' ); ?&gt;"&gt;&lt;?php _e( '삭제', 'my' ); ?&gt;&lt;/a&gt; | &lt;/span&gt;   It is a simple button.  I want to make this into a shortcode so that I can use it anywhere where appropriate.  Any suggestions?  Thanks. What are the best books to study Neural Networks from a purely mathematical perspective? I am looking for a book that goes through the mathematical aspects of neural networks, from simple forward passage of multilayer perceptron in matrix form or differentiation of activation functions, to back propagation in CNN or RNN (to mention some of the topics).  Do you know any book that goes in depth into this theory? I've had a look at a couple (such as Pattern Recognition and Machine Learning by Bishop or Deep Learning by Goodfellow, Bengio and Courville) but still have not found a rigorous one (with exercises would be a plus). Do you have any suggestions? Why didn't Harry die in the dark forest? Use of var keyword in C# Prove that $\lambda = 0$ is an eigenvalue if and only if A is singular. I'm trying to prove that statement: Prove that $\lambda = 0$ is an eigenvalue if and only if $A$ is singular.  I'm not sure if my proof is totally correct:  Suppose that $\lambda = 0$ if det(A) = $\lambda_1 \cdot \lambda_2 . . .\lambda_n = 0$ then A is singular.  If anyone could show me a better proof that would help. Quotient ring of Gaussian integers $\mathbb{Z}[i]/(a+bi)$ when $a$ and $b$ are NOT coprime The isomorphism $\mathbb{Z}[i]/(a+bi) \cong \Bbb Z/(a^2+b^2)\Bbb Z$ is , when the integers $a$ and $b$ are coprime. But what happens when they are not coprime, say $(a,b)=d&gt;1$?      — For instance if $p$ is prime (which is not coprime with $0$) then $$\mathbb{Z}[i]/(p) \cong \mathbb{F}_p[X]/(X^2+1) \cong \begin{cases} \mathbb{F}_{p^2} &amp;\text{if } p \equiv 3 \pmod 4\\ \mathbb{F}_{p} \times \mathbb{F}_{p} &amp;\text{if } p \equiv 1 \pmod 4 \end{cases}$$ (because $-1$ is a square mod $p$ iff $(-1)^{(p-1)/2}=1$).  — More generally, if $n=p_1^{r_1} \cdots p_m^{r_m} \in \Bbb N$, then  each pair of integers $p_j^{r_j}$ are coprime, so that by CRT we get $$\mathbb{Z}[i]/(n) \cong \mathbb{Z}[i]/(p_1^{r_1}) \times \cdots \times \mathbb{Z}[i]/(p_m^{r_m})$$  I was not sure how to find the structure of $\mathbb{Z}[i]/(p^{r}) \cong (\Bbb Z/p^r \Bbb Z)[X] \,/\, (X^2+1)$ when $p$ is prime and $r&gt;1$.  — Even more generally, in order to determine the structure of $\mathbb{Z}[i]/(a+bi)$ with $a+bi=d(x+iy)$ and $(x,y)=1$, we could try to use the CRT, provided that $d$ is coprime with $x+iy$ in $\Bbb Z[i]$. But this is not always true: for $d=13$ and $x+iy=2+3i$, we can't find Gauss integers $u$ and $v$ such that $du + (x+iy)v=1$, because this would mean that $(2+3i)[(2-3i)u+v]=1$, i.e. $2+3i$ is a unit in $\Bbb Z[i]$ which is not because its norm is $13 \neq ±1$.  — I was not able to go further. I recall that my general question is to known what $\mathbb{Z}[i]/(a+bi)$ is isomorphic to, when $a$ and $b$ are integers which are not coprime (for instance $a=p^r,b=0$ or $d=(a,b) = a^2+b^2&gt;1$).  Thank you for your help! How are second order nonlinear ordinary differential equations solved? Something special about energy eigenstates when it comes to time evolution? A particle is subject to an infinite square well potential with  $$V(x)= \begin{cases}  0  &amp;   −a \lt x \lt a\\   \infty &amp;  \,\,\,\,\text{otherwise} \end{cases}$$  At a time $t=0$ its wavefunction is given by $$\psi(x, t=0)=\frac{1}{\sqrt{5a}}\cos\left(\frac{\pi x}{2a}\right)+\frac{2}{\sqrt{5a}}\sin\left(\frac{\pi x}{a}\right)$$       (a) What are the possible results of an energy measurement at $t = 0$, and with what probabilities?     Re-writing the terms in $\psi(x,t=0)$ as $$u_1(x)=a^{-1/2}\cos\left(\frac{\pi x}{2a}\right)\qquad \text{&amp;} \qquad u_2(x)=a^{-1/2}\sin\left(\frac{\pi x}{a}\right)$$ such that $$\psi(x,t=0)= \frac{1}{\sqrt{5}}u_1(x)+\frac{2}{\sqrt{5}}u_2(x)$$ with energies $$E_1=\frac{\hbar^2 \pi^2}{8ma^2}\qquad \text{&amp;} \qquad E_2=\frac{\hbar^2 \pi^2}{2ma^2}$$ and probabilities $$P(E_1)=\frac15 \qquad \text{&amp;} \qquad P(E_2)=\frac45$$       (b) If no measurement is performed, what is the wavefunction $\psi(x, t)$ at all times $t$? What are the possible energies and their probabilities if a measurement is first performed at time $t$?     At a time $t$ the wavefunction is given by $$\psi(x, t=0)=\frac{1}{\sqrt{5a}}\cos\left(\frac{\pi x}{2a}\right)\exp\left(\frac{-i E_1 t}{\hbar}\right)+\frac{2}{\sqrt{5a}}\sin\left(\frac{\pi x}{a}\right)\exp\left(\frac{-i E_2 t}{\hbar}\right)$$    The problem is that I cannot answer the second part of the question (b).    The answer states that:      Because the two terms are energy eigenstates, the relative probabilities do not change and are as in the previous part.     I have some questions about the above statement: why does an "energy eigenstate" mean that the probablities don't change with time? Or, put in another way, does a "momentum eigenstate" (for example) have constant relative probabilities when measured at any time?   The answer seems to be implying there is something special about energy eigenstates when it comes to time evolution. The eigenvalues of energy measurements don't seem to change regardless of how many times you measure them, and no matter how long you wait until you measure them. I'm not sure if this is the case, but could someone please explain why all quantum operators (except Hamiltonian) do not exhibit this behaviour. What is the best way to initialize a private, static data member in C++?  I tried this in my header file, but it gives me weird linker errors:  class foo {     private:         static int i; };  int foo::i = 0;   I'm guessing this is because I can't initialize a private member from outside the class.  So what's the best way to do this? Derivatives of $ \frac{1}{r} $ and Dirac delta function I am trying to understand the formula \begin{equation} \nabla^2\left(\frac{1}{|{\bf r}-{\bf r}'|}\right) = - 4 \pi \delta(\bf{r}-\bf{r}'), \qquad\qquad {\rm (I)} \end{equation} where ${\bf r}=(x,y,z)$. This is something heavily used in electrostatics and the steps to 'show' this is often the following: The first derivative reads \begin{equation} \nabla \frac{1}{| {\bf r} - {\bf r}' |} = - \frac{ {\bf r} - {\bf r}'}{| {\bf r} - {\bf r}'|^3} \end{equation} And taking the second derivative gives zero, except for the singularity at ${\bf r} = {\bf r'}$. Then from the divergence theorem we have \begin{equation} \int dV \,  \nabla^2 \frac{1}{| {\bf r} - {\bf r'}|} = \int dS  \,\,{\bf n} \cdot ( \nabla\frac{1}{|{\bf r} - {\bf r}'|}) = -4 \pi \end{equation} where the integration is performed over a sphere centered at ${\bf r}'$. Q1: Is there a more direct proof for equation (I)? Then my main question is about the separate second-order differentials. For instance, we can obtain, by direct computation \begin{equation} \partial_x^2 \, \frac{1}{| {\bf r} - {\bf r}'|} = \frac{ 3 (x-x')^2 }{| {\bf r} - {\bf r'} |^5} - \frac{1}{| {\bf r} - {\bf r}'|^3} \end{equation} Q2: Should there be a $\delta$ function on the r.h.s of this equation? Wheel going badly out of true on final tightening On two occasions (same wheel, loosened everything off and re-did the whole thing after the first time) as I've applied a final half turn to tighten the spokes round the wheel it's gone from being pretty laterally true (within about 0.5 mm) to badly out of true (probably a couple of mm or more out).  The simplest explanation would be that I've managed to mess up by missing spokes/over under-tightening some of them, but I'm fairly sure that's not the case.  What else could cause this?  This is a rear wheel with a fair amount of dish. I'm worried that I might be over-tightening. On both occasions I decided to do a final half turn as the non drive side seemed a little loose, but I was concerned the drive side might be over tight. Could this cause a sudden change in trueness?  I've got the wheel back to a reasonable state, but I'm no longer sure I have even tension in the spokes. how to hide mesh but keep hair particles How can I minimize Thunderbird 60.2.1 to tray after "MinimizeToTray revived" add-on stopped working? After update, my Thunderbird stopped getting minimized with the "MinimizeToTray revived" add-on. Is there any way to minimize my Thunderbird? Any other add-on that works with the new version? iOS: Your passcode is required to enable Touch ID Occasionally, when unlocking my iPhone or iPad, I get the following message:     Your passcode is required to enable Touch ID   Now this is not after a number of failed attempts or turning the device off. The device was used within the last 12 hours. Two of the devices are less than 2 months old, and one is a year old. Everything is up to date. It appears to be happening more-or-less at random.  Does anybody know why this message might appear? Metapost label based on variable value I want to label a scale based on a variable value and I wrote a metapost code like this.  $ := 1; for i = -.3cm step .6cm until 3.6cm:     label.bot(str$,(i,-3.7cm));     $ := incr($); endfor;   It just labels "$" instead of its value. How to output the variables value? How to create a Customized Ubuntu Server ISO? I've read the , and I don't get it. I am really interested, but I've read the explanation there a couple of times and I still don't get it how the Duff's device works.  What would a more detailed explanation be?