Understanding how values are passed to and returned from methods
Is Java "pass-by-reference" or "pass-by-value"?
Quantum mechanics and everyday nature Is there a phenomenon visible to the naked eye that requires quantum mechanics to be satisfactorily explained? I am looking for a sort of quantic Newtonian apple. Shannon confusion and diffusion concept I read the document(not the whole document) from Shannon where he speaks about the concepts of confusion and diffusion. I read in many places(not in the document but around the internet) that confusion is enforced using substitution. Diffusion is enforced using permutation/transposition. Ciphers must use both of them because either confusion or diffusion alone are not enough. I read that a substitution cipher can apply by itself confusion(only). Permutation/Transposition applies by itself diffusion(only). It's precisely the last case that bothers me: Can a permutation/transposition cipher by itself apply diffusion?  Shannon explains diffusion as a property that spreads statistic properties of text all over the text preventing statistic analysis. It's frequently translated to: an alteration to a plaintext symbol affects many cipher text symbols. Assuming permutation of bits or characters, how can diffusion be achieved by simple permutation? I mean, if you permute bits, there will be no other bits affected. But if you consider a symbol a character and you permute bits, a change in a character will affect many other characters. It's a question of what is a symbol.  I also read versions of this diffusion concept where the point was just changing bits order just to avoid pattern analysis of the text. But, where is the avalanche effect in simple permutation?  So, what is the correct definition and the implications of diffusion?  I hope you understand what is troubling me.  Thank you once more Display error message if same record exist with combination of some fields? I have taken three fields from case object called AccountName, IntegrationTo__c and SfType__c (checkbox).  I have created one case record with a specific combination of three fields.  For the second time I create a record with that combination, then  display error message only if SfType__c is true in first record otherwise allow  for record creation.  trigger AvoidDuplicate on Case(before insert)  {          set&lt;string&gt; newNameSet = new set&lt;string&gt;();     newNameSet = new set&lt;string&gt;();      set&lt;string&gt; newEmailSet = new set&lt;string&gt;();      set&lt;string&gt; dbNameSet = new set&lt;string&gt;();      set&lt;string&gt; dbEmailSet = new set&lt;string&gt;();      for(Case newLead : trigger.new){          newNameSet.add(newLead.Account.Name);          newEmailSet.add(newLead.IntegrationTo__c);      }      for(Case dbLead : [select id, Case.Account.Name, IntegrationTo__c from Case where IntegrationTo__c IN: newEmailSet OR Case.Account.Name IN: newNameSet]){          dbNameSet.add(dbLead.Account.Name);          dbEmailSet.add(dbLead.IntegrationTo__c);      }      for(Case newLead : trigger.new){          if(dbNameSet.contains(newLead.Account.Name) &amp;&amp; dbEmailSet.Contains(newLead.IntegrationTo__c))              newLead.addError('You are inserting Duplicate Case');      }  }   i wrote this this not checking the account field name and integration__c values only with combination of account and integration__c shows error Ideal charging / discharging percentage for maximum battery life? One of my friends has a relatively new Samsung smartphone. He has this app that notifies him whenever the charging is up to 80%, and tells him to unplug the charger.  He tells me that it will increase the number of charging cycles for his battery. He says that if he lets it charge all the way up to 100%, it will mean he has to replace the battery of the phone more often.  Is this true?  Somehow, I feel this is a thing of the past. I thought the internal architecture of batteries these days was made so that it wouldn't drop too low or too high. (In other words, when the phone is at 100%, it isn't really 100%. It's what the battery can safely be charged to in order not to degenerate too much.)  Here's a  which taught me something about this. Number of ways a natural number can be written as sum of smaller natural number It is easy to realize that given a natural number N the number of doublets that sum N are $\frac{N+(-1)(N \pmod 2)}{2}$ , so I thought I could reach some recursive formula in the sense that found the number of doublets I could find the number of triplets and so on ...,  example: N=3 the only doublet is 2+1=3 -not said yet but 2+1, and 1+2 count as one- then I could count the number of way the number 2 can be expressed as the indicated sum and got the total number of ways 3 can be written as a sum. But this seems not so efficient, so I was wondering if there is other way to attack the problem and if there is some reference to this problem such as if it is well known its used, once I read that this have a chaotic behavior, and also read It was used in probability but don't remember where I got that information. So if you know something I would be grateful to be notice, thanks in advance. Graphical interpretation of LASSO In the review page, it shows stats of recent reviewers. But it is showing wrong stats. Because today (on Monday) it shows week count 53 (on Meta Stack Overflow) which is impossible as there is a limit of 20 reviews per day.    PS: This bug   and . But the bug has occurred again. Spam iCloud Calendar Invitations Will self-citation be viewed as self-promotion in academia? As we know, citation counts are important to judge one's research activity. Is it good to cite one's previous works? Will it be viewed as an act of advertisement or self-promotion? Prove $e^x - e^y \leq e |x-y|$ for $x$ belonging to $[0,1]$ I'm not sure how to go about this. Does it involve using MVT?  I got as far as saying $e = \frac{e^x - e^y}{x-y}$. Integral $\int\frac{dy}{(y^2 + ay + b)^{3/2}}$ Need the indefinite integral with $a,b$ constants. This is not a homework question. Need it for a physics problem. Estimating the integrated Tchebychev function and calculating its error Reset post score to 0 on migration This story had a researcher landing on an uncharted planet to see if it was any good for mining some type of mineral/metal.  Whilst there he encounters this type of ball that chases him all over the planet. He ends up finding this ball’s collection of other things it has caught including animals all the way back to the dinosaurs.  On the ball it has the writing '+/-7.  In the end it chases him for so long that he weighs too little for the balls 'collection'.  Any ideas greatly appreciated. A problem of missing energy when charging a second capacitor A capacitor is charged. It is then connected to an identical uncharged capacitor using superconducting wires. Each capacitor has 1/2 the charge as the original, so 1/4 the energy - so we only have 1/2 the energy we started with. What happened? my first thoughts were that the difference in energy is due to heat produced in the wire. It may be heat, or it may be that this is needed to keep equilibrium. How to install Unity 8? I'm using Ubuntu 14.04 and found out that we can install Unity 8 on it. Will Unity 8 replace Unity 7 once I install it? And if it does can I switch back to Unity 7 if I want? How would one go about it? Missing Schengen entrance stamp Last night I took a night train from Romania to Hungary. I shared a compartment with another American backpacker (and others.) The border crossing on the Romanian side was normal -- all of our passports were stamped and the border officer recorded our data in his notepad. On the Hungarian side, some sort of commotion broke out further down the train car while we were being processed. The officer who was scanning and stamping our passports left and never came back. As a result, the other American backpacker never had her passport scanned or stamped.  What sort of difficulties might she run into since her passport has not been recorded as entering the schengen zone, nor does she have an extra stamp? What might get options be now, from within Schengen, to get her entrance recorded?  (When I say "scanned", the officers had hand-held devices that read the passport biometrics and I assume, recorded some sort of data somewhere.) Calculate sum of series $\sum \frac{n^2}{n!}$ I have to calculate sum of series $\sum \frac{n^2}{n!}$. I know that $\sum \frac{1}{n!}=e$ but I dont know how can I use that fact here.. When a divination wizard character uses their Portent ability:     Starting at 2nd level when you choose this school, glimpses of the   future begin to press in on your awareness. When you finish a long   rest, roll two d20s and record the numbers rolled. You can replace any   attack roll, saving throw, or ability check made by you or a creature   that you can see with one of these foretelling rolls. You must choose   to do so before the roll, and you can replace a roll in this way only   once per turn.   ... to replace a roll, can a player with the Lucky Feat:     Whenever you make an attack roll. an ability check, or a saving throw,   you can spend one luck point to roll an additional d20. You can choose   to spend one of your luck points after you roll the die, but before   the outcome is determined. You choose which of the d20s is used for   the attack roll, ability check, or saving throw.      You can also spend one luck point when an attack roll is made against   you. Roll a d20, and then choose whether the attack uses the attackers   roll or yours.      If more than one creature spends a luck point to influence the outcome   of a roll, the points cancel each other out; no additional dice are   rolled.   ... use the Luck Roll to replace the result? Or does the Portent trump all rolls and simply give you the final outcome?  This question spun off from  on .  Some relevant points:  .  Mike Mearls tends to believe that luck can triumph in some cases, but admits this is , and further seems to conflate the question with .  I would suggest reading the linked discussion before formulating an answer. There's some good thought there. Use mathematical induction to prove that any integer $n\ge2$ is either a prime or a product of primes. Use  strong mathematical induction to prove that any integer $n\ge2$ is either a prime or a product of primes.    I know the steps of weak mathematical induction... Basis step: $p(n)$ for $n=1$ or any arbitrary $n_0$ ... show that it is true Inductive hypothesis: $p(n)$ for $n=k$ ... Assume that it is true for $n=k$ Inductive step: $P(n)$ for $n=k+1$ ... Show that this is true for $n=k+1$