preconditions

dafny pre-condition failure

由 前提是你 提交于 2021-01-28 01:33:26
问题 I'm trying to run a dafny verified version of BFS (from here) My input graph is perfectly fine, but for some reason it fails the pre-condition check. Here is the permalink And for self completeness here is the graph definition + validity conditions class Graph { var adjList : seq<seq<int>>; constructor (adjListInput : seq<seq<int>>) { adjList := adjListInput; } } function ValidGraph(G : Graph) : bool reads G { (forall u :: 0 <= u < |G.adjList| ==> forall v :: 0 <= v < |G.adjList[u]| ==> 0 <=

Check in range precondition

由 你说的曾经没有我的故事 提交于 2020-01-13 05:22:06
问题 I like guava preconditions, but what I really need from it is one more method - check that the number is in range. Smt like this //probably there should be checkStateInRange also public static void checkArgumentInRange(double value, int min, int max) { if (value < min || value > max) { throw new IllegalArgumentException(String.format("%s must be in range [%s, %s]", value, min, max)); } } I believe I'm not alone and it's a pretty common case. But such method doesn't exist. Is there any reasons

General Minimum RESidual (GMRES) with ILU preconditioner

由 痞子三分冷 提交于 2020-01-04 09:06:17
问题 I'm trying to implement the ILU preconditioner in this GMRES code I wrote (in order to solve the linear sistem Ax = b. I'm trying with an easy tridiagonal SPD matrix of dimension 25x25. As you can see I'm calculating the preconditioner with spilu method. The code is running without error, but the solution is clearly wrong since, at the end of the code, I'm printing the norm of b and the norm of the product A*x. They are not nearly the same.. The code Run fine without preconditioner and

Checking Clojure pre-conditions without running the function?

由 大憨熊 提交于 2019-12-24 10:41:41
问题 I have one function that does some (possibly lengthy) work (defn workwork [x] ...) and some other functions to check if the call will succeed ahead of time (defn workwork-precondition-1 [x] ...) . The precondition functions should be evaluated every time workwork is called (e.g. using :pre ). The precondition functions should also be collected (and:ed) in a single function and made available to client code directly (e.g. to disable a button). Which is the idiomatic way to solve this in

What are the options for precondition checking in Haskell

由 天大地大妈咪最大 提交于 2019-12-23 15:28:55
问题 This is a simple question with a complex answer I presume. A very common programming problem is a function that returns something, or fails precondition checks. In Java I would use some assert function that throws IllegalArgumentException at the beginning of the method like so: { //method body Assert.isNotNull(foo); Assert.hasText(bar) return magic(foo, bar); } What I like about this is that it is a oneliner for each precondition. What I don't like about this is that an exception is thrown

Scala avoid using null

由 泄露秘密 提交于 2019-12-23 08:57:05
问题 I hava a project on github that is analysed by codacy . The analysis suggest to "Avoid using null" for the following line of code: def doSomethingWithPath(path:Path) = { require(path != null, "Path should not be null") //<-to avoid ... } What is the simplest scala idiomatic thing to do to fix it? 回答1: I would keep it as is. You aren't really using null here, just guarding against it. The alternative could be to just delete that line altogether, and decide to not handle the null at all.

how do i explain that if (xyz == null) checks are not “protective”

由 眉间皱痕 提交于 2019-12-21 18:14:03
问题 i have a few developers who constantly put If null checks For example: Run(Order order) { if (order == null) return; } in their code as they think they are protecting their class if someone passes in a parameter that is null. I am trying to tell them the flaw in their logic because if someone is passing in null in this case, its most likely an issue with the consumer code and instead of this class throwing an exception and failing fast, it gracefully handles the bad behavior of the consumer

how do i explain that if (xyz == null) checks are not “protective”

由 五迷三道 提交于 2019-12-21 18:13:28
问题 i have a few developers who constantly put If null checks For example: Run(Order order) { if (order == null) return; } in their code as they think they are protecting their class if someone passes in a parameter that is null. I am trying to tell them the flaw in their logic because if someone is passing in null in this case, its most likely an issue with the consumer code and instead of this class throwing an exception and failing fast, it gracefully handles the bad behavior of the consumer

Guava库学习：学习使用Preconditions工具类进行代码的校验

由 房东的猫 提交于 2019-12-15 23:49:02
【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 链接地址： http://www.xx566.com/detail/127.html Preconditions是guava提供的用于进行代码校验的工具类，其中提供了许多重要的静态校验方法，用来简化我们工作或开发中对代码的校验或预 处理，能够确保代码符合我们的期望，并且能够在不符合校验条件的地方，准确的为我们显示出问题所在，接下来，我们就来学习使用Preconditions 进行代码校验。 翻开Preconditions的源码，我们看到，guava进行了大量方法的重载，组成了Preconditions工具类，下面我们先简单的了解一下，所有的14个静态方法，如下： checkArgument(boolean expression)：用来校验表达式是否为真，一般用作方法中校验参数 checkArgument(boolean expression, @Nullable Object errorMessage)：校验表达式是否为真，不为真时显示指定的错误信息。 checkArgument(boolean expression, @Nullable String errorMessageTemplate, @Nullable Object... errorMessageArgs)：校验表达式是否为真，不为真时显示错误信息

Lognormal random numbers in specific range in Matlab

由 我怕爱的太早我们不能终老 提交于 2019-12-13 06:33:09
问题 I want to develop a lognormal distribution with range [0.42,1.19], whose few elements are given as D=[1.19,1.00,0.84,0.71,0.59,0.50,0.42] . The mean should be 0.84 and standard deviation as small as possible. Also given is that the 90% of cdf (=90% of the grains) lies between 0.59 and 1.19 . Once I know all the elements of this lognormal distribution which incorporate the given conditions I can find its pdf, which is what I require. Here are simple steps I tried: D=[1.19,1.00,0.84,0.71,0.59,0
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