Why do I get this function call error on an non-object when I am calling a function on an object?
mysqli_fetch_assoc() expects parameter / Call to a member function bind_param() errors. How to get the actual mysql error and fix it?
Why are potential differences equal across two capacitors in parallel, but charge on each capacitor is not? Two or more capacitors are said to be connected in parallel if each one of them is connected across the same two points. In a parallel combination of capacitors potential difference across each capacitor is same but each capacitor will store different charge. Why is this true? Why is the potential difference across each capacitor in parallel the same and why will each capacitor store different charge?  Also, in series, why are Potential difference across each capacitor different, while charge is the same? Why does the speed of light in vacuum have no uncertainty? I could understand that the definition of a second wouldn't have an uncertainty when related to the transition of the Cs atom, so it doesn't have an error because it's an absolute reference and we measure other stuff using the physical definition of a second, like atomic clocks do.  But why doesn't the speed of light have uncertainty? Isn't the speed of light something that's measured physically?  Check out that . errors upgrading from 14.04 to 16.04 about Unknown Multi-Arch type for compiz, libkf5akonadisearch-bin packages I'm trying to upgrade my 14.04 machine to 16.04 using do-release-upgrade. After downloading the package lists for wily, I see the following errors:  Unknown Multi-Arch type 'no' for package 'compiz-core' Unknown Multi-Arch type 'no' for package 'compiz-gnome' Ignoring Provides line with DepCompareOp for package python-cffi-backend-api-max Ignoring Provides line with DepCompareOp for package python-cffi-backend-api-min Ignoring Provides line with DepCompareOp for package python3-cffi-backend-api-max Ignoring Provides line with DepCompareOp for package python3-cffi-backend-api-min Unknown Multi-Arch type 'no' for package 'libkf5akonadisearch-bin' Ignoring Provides line with DepCompareOp for package php-psr-http-message-implementation Ignoring Provides line with DepCompareOp for package php-psr-log-implementation Ignoring Provides line with DepCompareOp for package php-math-biginteger Unknown Multi-Arch type 'no' for package 'compiz-core' Unknown Multi-Arch type 'no' for package 'compiz-gnome' Ignoring Provides line with DepCompareOp for package python-cffi-backend-api-max Ignoring Provides line with DepCompareOp for package python-cffi-backend-api-min Ignoring Provides line with DepCompareOp for package python3-cffi-backend-api-max Ignoring Provides line with DepCompareOp for package python3-cffi-backend-api-min Unknown Multi-Arch type 'no' for package 'libkf5akonadisearch-bin' Unknown Multi-Arch type 'no' for package 'compiz-core' Unknown Multi-Arch type 'no' for package 'compiz-gnome' Unknown Multi-Arch type 'no' for package 'compiz-core' Unknown Multi-Arch type 'no' for package 'compiz-gnome' You may want to run apt-get update to correct these problems   It then proceeds to abort the installation. The suggested run of apt-get update doesn't seem to do anything. Googling for the above error messages yielded others having similar problems when upgrading to other, previous releases, although I've not come across any apparent fixes. It's suggested that an apt upgrade could fix the problem, but I don't see a way to easily do that (it's up to date with the latest trusty package).  What should I do in order to upgrade directly to 16.04? Escaped line break tag in tooltip on election page How can I set up password-less SSH login? Reputation has been changed but not reflected on tooltip. What is the effect where some objects are a single bright color but the rest is black and white? There is an option to filter only one color (R,G,B,Y) in my camera. What I want to know is can this effect be achieved in photoshop? And what is this called? I tried googling monochrome and came up with nothing. My camera calls it part color. "Was" or "were" for "half a dozen" In Microsoft Word, the following sentence is flagged.  It tells me to use "was" instead of "were"     There were half a dozen books strewn about the floor.   I would think that you would use "were" since it's a quantity more than one.  You wouldn't say, "There was twelve books strewn about the floor."  Does the use of the "half" modify it somehow? Given two ciphertexts $c_1 = enc(p_1)$ and $c_2= enc(p_2)$ using any additive homomorphic encryption scheme (or specifically Paillier).   Can we find out whether the underlying plaintexts $p_1,p_2$ are equal without decrypting $c_1,c_2$ i.e. homomorphically? I think the answer is yes but I know a lot of people disagree. So, I would like to ask these people when exactly does it stop being me.  Let's say I want to upload my brain into a computer using the following procedure:  I have each of my neurons replaced by electronic neurons. By electronic neurons I mean chips with the necessary hardware and software to perform the exact same function that the neuron being replaced was performing. This means that given the same inputs that the biological neuron was given it would produce the same outputs. Then I connect that electronic neuron to all the neurons that former biological neuron was connected to.   At the end of this process is it still me? If not when did it stop being me? When one neuron was replaced? When 1,000 were replaced? When 1,000,000 were replaced?  (assuming it is still me)  Then, I divide these electronic neurons into groups and for each group I perform the following:   Write software to simulate the group of electrical neurons in my computer such that given the same inputs that go into the group of electronic neurons in my brain, it will produce the same outputs. Replace each group of neurons with another chip that communicates with my computer. Each of the chips will communicate to the corresponding software module in order to determine how to transform its inputs into the necessary outputs. Connect all of the inputs and outputs of the group of electronic neurons to that new chip.   At the end of this process is it still me? If not when did it stop being me? When one group was replaced? When 1,000 were replaced? When 1,000,000 were replaced?  (assuming it is still me) Now, what I have is a bunch of these new chips in my head, connected to each other and for each of these chips I have a small neural network software module in my computer. So, now for each pair of chip/software module I do this:   Transfer all connections going into and out of the chip into the computer version (i.e. connect the software module to the other software modules that represent the other chips that this chip is connected to) Disconnect the chip from the other chips and remove it   At the end of this process is it still me? If not when did it stop being me? When one of the new chips was replaced? When 1,000 were replaced? When 1,000,000 were replaced?  If it is still me then I have successfully moved my brain into a computer without ceasing being myself.  So, again the question is if at the end it is not me anymore when exactly does it stop being me and why does it stop being me?  EDIT: This question assumes that our universe and everything in it (including ourselves) follows the (testable) laws of physics. As it stands it also assumes that neuroscience is mostly right, although the question could also be considered without that requirement if instead of neural simulations we were to implement physics simulation of the brain. Of course this is a lot less practical. However, if your view is that our minds have a supernatural component then the question does not make any sense.  It was also pointed out that this is related to the Ship of Theseus, i.e. is something still the same if all its parts have been changed. With regards to that I think it is useful to consider that most of the cells in our body (not including brain cells) are regularly replaced anyway and some people even get entire organs replaced. Yet, we don't say that they stopped being themselves. Note, however, that if you are assuming a supernatural component of the mind that this explanation is not really adequate or relevant. Divisibility by 7 rule, and Congruence Arithmetic Laws I have seen other criteria for divisibility by 7. Criterion described below present in the book Handbook of Mathematics for IN Bronshtein (p. 323) is interesting, but could not prove it. Let $n = (a_ka_{k-1}\ldots a_2a_1a_0)_{10} = \displaystyle{\sum_{j=0}^{k}}a_{k-j}10^{k-j}$. The expression $$ Q_{3}^{\prime}(n) = (a_2a_1a_0)_{10} - (a_5a_4a_3)_{10} + (a_8a_7a_6)_{10} -\ldots  $$ are called alternating sum of the digits of third order of $n$. For example,  $$ Q_{3}^{\prime}(123456789) = 789-456+123=456 $$ Proposition: $7 | n \ \Leftrightarrow \ 7 | Q_{3}^{\prime}(n)$.  proof. ??  Thanks for any help. Inverse images of images, images of inverse images of a set of vectors What can be said about$\ f^{-1}(f(S))$ and$\ S$, where$\ f(S):=\{f(x):x \in S\}$?   I feel as if$\ f^{-1}(f(S))$ will be smaller than or equal in size (number of elements) to$\ S$.  For example, if$\ f(x)=x$, then$\ f(\{-1, 0, 1, 2\})=\{-1, 0, 1, 2\}$and$\ f^{-1}(f\{-1, 0, 1, 2\})=\{-1, 0, 1, 2\}$ (same size).  But if$\ f(x)=x^2$, then$\ f(\{-1, 0, 1, 2\})=\{0, 1, 4\}$ and$\ f^{-1}(f\{0, 1, 4\})=\{0, 1, 2\}$, which is a little bit smaller than$\ S$.   What can be said about$\ f(f^{-1}(U))$ and$\ U$, where$\ f^{-1}(U):=\{x \in X:f(x) \in U\}$?   The same size as each other? Always?? I am having a hard time with the following real analysis qual problem.  Any help would be awesome.  Suppose that $f \in L^p(\mathbb{R})$, where $1\leq p&lt; + \infty$. Let $T_r(f)(t)=f(t−r)$. Show that $\lim_{r \to 0} \|T_rf−f\|_{L_p} =0$, that is $$ \lim_{r\to 0} \left( \int_{\mathbb R} |f(t-r) - f(t)|^p \mathrm d t\right)^{1/p} =0.$$ Select top 10 records for each category I want to return top 10 records from each section in one query. Can anyone help with how to do it?  Section is one of the columns in the table.  Database is SQL Server 2005. I want to return the top 10 by date entered.  Sections are business, local, and feature.  For one particular date I want only the top (10) business rows (most recent entry), the top (10) local rows, and the top (10) features. How can you use optional parameters in C#? Note: This question was asked at a time when C# did not yet support optional parameters (i.e. before C# 4).  We're building a web API that's programmatically generated from a C# class. The class has method GetFooBar(int a, int b) and the API has a method GetFooBar taking query params like &amp;a=foo &amp;b=bar.   The classes needs to support optional parameters, which isn't supported in C# the language. What's the best approach? How to reduce the spacing in chemical symbols? Currently, if want to write a chemical symbol, for example, ${}^{239}Np$, this is what I type in: {}^{239}Np. The result:    But it looks bad, I feel as if the "N" and "p" should be closer, or a different font should have been used.  How could I make better looking chemical symbols? Currently I am using mainly the MathJax of the SE, but sometimes I use other TeX as well. Rear fender angle For a 20" rear wheel with a this kind of fender, what would be the best angle to install it to minimize the spray on one's butt/legs? why does loop-cut-and-slide ignore some faces but not others? Linux - why do the su and sudo binaries need to be set-UID root? I am trying to find the correct reason for the stated question. My understanding is that:   sudo needs to read the /etc/sudoers file which is only readable by root, which is why it needs to be set-UID root su is going to create a new shell with a different real and effective UID, and needs to check the password. To check the password, it needs to read /etc/shadow, which is why it needs to be set-UID root. After checking password, it would need to call setuid() on the forked process, and to use an arbitrary UID argument, its parent process must have root as effective UID, so this also makes another reason.   Are the above reasons correct ? how to read xml file from url using php