Converting System::String to Const Char *
how to convert System::String to const char*?
How to calculate the signal-to-noise ratio (SNR) in an image? I am working with an image X, I apply the "adaptive median filter" in it and I get the image Y. I'd like to measure the SNR in both in order to evaluate the quantity of noise deleted.   I know the formula to calculate the SNR is:   SNR = Psignal / Pnoise  but I don't know how to get these values from both images I have. I was thinking in substract the image X from Y and get the noise value. But I am not sure about the method. I've searched the net for such information and found different command lines, like these ones:  sudo apt-get remove application sudo apt-get remove application*  sudo apt-get remove --purge application sudo apt-get remove --purge application*  sudo apt-get purge application sudo apt-get purge application*   So, what is the correct way? Is it necessary to use that "*"?  After that, I also found these commands:  sudo updatedb sudo locate application sudo rm -rf (file/folder name) How do I get the local machine name in C#? Can't find boot-repair package for the newest version of Ubuntu I know that I have to use some tweaking tool and then a extension for this. But all extensions that are suggested for this(Workspace grid, Workspace matrix), aren't available in the software center. Order of a homomorphism of groups Let $f: G \to H$ be a homomorphism of groups. Assume that $a\in G$ and $\operatorname{ord}(a)=n$. Prove that the order of $f(a)$ is a divisor of $n$. I know that if $H$ is a subgroup of $G$, then $$|G|=|H|\cdot|\text{distinct cosets of $H$}|$$ so $|H|$ must be divisor of $|G|$, but I don't understand how to apply that logic to homomorphisms (or if that will even work). Any help is appreciated! Give us better search-by-score syntax tl;dr: Give the score search operator ability to change between greater than and less than.  I just noticed that searching for score:0 turns up only question with a score equal to 0. Searching for score:1 gives everything with a positive score. (&gt;=1) I can live with these. But here's the big one: score:-1. I would expect it to give all the negatively scored posts - there is a minus sign in there. But it doesn't. It gives all the posts &gt;=-1. Greater than? So, my  is that we get more granular search options for score. For example,  score:1 would show all posts with score == 1 score:1+ would show everything score &gt;= 1 score:0 would show all posts with score == 0 score:-1 would show everything score == -1 score:-1- would show al posts where score &lt;= -1  In short, the operator after the number would show which direction to go with the matching. A minus sign means less than, a plus sign means greater than. No sign means exact. gwt java.lang.ExceptionInInitializerError Money making in Runescape How do you file a bug report for Windows? I have come across an issue that I feel is a  in Windows 7. What is the official process for submitting an issue to Microsoft from a consumers perspective as an end user of Windows? While finding escape velocity, does human mass counts as the mass of Earth? Escape velocity depends upon the mass of earth. my doubt is whether human mass adds into it or not? If it add then Earth's escape velocity would be increasing! Why am I getting "No such file or directory" when I try to execute a binary? I've searched for multiple forums for this questions and have seen different answers but so far, nothing have worked yet even from the ones I've seen here.  I want to extract a single file from a tar to a different directory.  I've tried this:  tar xvf file.tar -C /home/dir/ filename   or this:  tar -x filename -f file.tar -C /home/dir   But got these errors respectively:  x filename, 14826 bytes, 29 media blocks. File -C not present in the archive. File /home/dir not present in the archive.   and:  tar: /dev/rmt0: A file or directory in the path name does not exist.   The first extracted the file but in the same directory, not to the folder I wanted. Why bother with the dual problem when fitting SVM? I just installed Ubuntu 12.10 on an ASUS X401U, and after installation there is no list of wireless connections. I didn't have that problem with an installation on HP. What I can do to enable Wifi?  07:00.0 Network controller [0280]: Ralink corp. Device [1814:3290] I only get four video output options Even when I start a brand new file in Blender, I only get four video output file options: AVI raw, AVI JPEG, Frame Server, FFMpeg Video.  I am running version 2.78.5 (I'm using the beta so that I can use denoising.  How can I get access to all the other video outputs other people have? Like this: Why can't I import a file in the init.m file? How do I install a fingerprint reader on Lenovo ThinkPad? Why is any pgr_* routing function taking forever based on OSM data in an pgrouting enabled DB How to evaluate this infinite sum?  $$\sum_{n=1}^{\infty}\frac{1}{2^n-1}$$