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Find root of implicit function in MATLAB

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问题 I have an implicit function, for example: f(x,y) = x.^3 + x.*y + y.^2 - 36 I want to solve the root. So f(x,y) = 0 . Drawing the solution is easy: ezplot('x.^3 + x.*y + y.^2 - 36',[-10 10 -10 10]); However, I would like to have the data that is in the plot and not only the visual plot. So how do I find the data of the plot? i.e., how to get data OUT of a plot once it is made? 回答1: If you supply an output argument to ezplot , it will give you a line handle. One of the properties of line

Resolving Implicit for `Show` Typeclass Instance

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问题 I'm trying to make Gender implement the Show typeclass. scala> trait Gender extends Show[Gender] defined trait Gender scala> case object Male extends Gender defined object Male scala> case object Female extends Gender defined object Female Next, I defined a function that calls show on an implicit Show[A] . scala> def f[A : Show](x: A): String = implicitly[Show[A]].shows(x) f: [A](x: A)(implicit evidence$1: scalaz.Show[A])String Finally, I created an implicit class for Show[Gender] : scala>

Scala中隐式转换（implicit conversion）的优先顺序

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在学习Scala的时候，隐式转换（implicit conversion）这个特性让我实在是闹不住啊。于是乎一边试用一边感慨：真的是太强大，太方便了。不过，越是强大且方便的东西，越容易用出毛病来。在我不求甚解的情况下，毛病就来了，我把它称为隐式转换优先顺序问题：假设我们有一个表示文本的行数的类LineNumber： class LineNumber ( val num : Int ) 我们可以用这个类来表示一本书中每一页的行数： val lineNumOfPage1 = new LineNumber(112) val lineNumOfPage2 = new LineNumber(120) 上面的代码分别表示了第一页和第二页的行数。当然，我们也应该可以将它们相加，得到这两页的总行数： val totalLineNum = lineNumOfPage1 + lineNumOfPage2 这样的话，我们的LineNumber类里就应该有一个 “+” 方法来将两个对象相加： class LineNumber ( val num : Int ) { def + ( that : LineNumber ) = new LineNumber( this.num + that.num ) } 从直观上讲，我们甚至可以直接用整数来和LineNumber相加： val

Scala and cats: Implicit conversion to identity monad

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问题 I have a function that computes sum of squares for numeric types as shown below. import cats.syntax.functor._ import cats.syntax.applicative._ import cats.{Id, Monad} import scala.language.higherKinds object PowerOfMonads { /** * Ultimate sum of squares method * * @param x First value in context * @param y Second value in context * @tparam F Monadic context * @tparam T Type parameter in the Monad * @return Sum of squares of first and second values in the Monadic context */ def sumOfSquares[F[

Enforcing precedence in implicit instances in Scala

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问题 This is a follow-up on the question Scala implicit typeclass precedence in companion objects. Suppose that I have two traits, Trait2 extends Trait1 . Each trait has a specific typeclass instance of Eq . I'd like to let the precedence of the typeclass instance of Trait2 to be higher than tha of Trait1 . However, the code below (the LowPriorityImplicits trick) does not work. trait Eq[-A] { def eq(a: A, b: A): Boolean } object Eq { implicit object IntEq extends Eq[Int] { def eq(a: Int, b: Int) =

When do these load DLLs : Implicit Linking VS Explicit Linking

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问题 I thought Implicit linking loads a DLL as soon as the application starts because it is also called "load-time dynamic linking". But I found some strange explanations below from the link here(https://msdn.microsoft.com/en-us/library/253b8k2c(VS.80).aspx). Implicit Linking Like the rest of a program's code, DLL code is mapped into the address space of the process when the process starts up and it is loaded into memory only when needed. As a result, the PRELOAD and LOADONCALL code attributes

Scala - How can I exclude my function's generic type until use?

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I have a map of String to Function s which details all of the valid functions that are in a language. When I add a function to my map, I am required to specify the type (in this case Int ). var functionMap: Map[String, (Nothing) => Any] = Map[String, (Nothing) => Any]() functionMap += ("Neg" -> expr_neg[Int]) def expr_neg[T: Numeric](value: T)(implicit n: Numeric[T]): T = { n.negate(value) } Instead, how can I do something like: functionMap += ("Neg" -> expr_neg) without the [Int] and add it in later on when I call: (unaryFunctionMap.get("abs").get)[Int](-45) Dan Getz You're trying to build

Implicit Conversions on Generic Trait

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I am implementing a datastructure and want the user to be able to use any type as key as long as he provides a suitable key type wrapping it. I have a trait for this key type. The idea is to have implicit conversions from base to key type and the other way round to (virtually) just use the base type. The trait looks like this: trait Key[T] extends Ordered[Key[T]] { def toBase : T // Further stuff needed for datastructure... } object Key { implicit def key2base[T](k : Key[T]) : T = k.toBase } Call site code could look like this: def foo[K <% Key[K]]( bar : Seq[K] ) = bar.sorted(0) Plan is that

implicit conversions that add properties to a type, rather than to an instance of a type

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I was reading through some older Scala posts to better understand type classes, and I ran across this one that seemed quite useful, but the example seems to have gotten stale. Can someone help me figure out the correct way to do what Phillipe intended ? Here is the code trait Default[T] { def value : T } implicit object DefaultInt extends Default[Int] { def value = 42 } implicit def listsHaveDefault[T : Default] = new Default[List[T]] { def value = implicitly[Default[T]].value :: Nil } default[List[List[Int]]] When copy/pasted and run in REPL, i get this> scala> default[List[List[Int]]]

Task not serializable while using custom dataframe class in Spark Scala

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问题 I am facing a strange issue with Scala/Spark (1.5) and Zeppelin: If I run the following Scala/Spark code, it will run properly: // TEST NO PROBLEM SERIALIZATION val rdd = sc.parallelize(Seq(1, 2, 3)) val testList = List[String]("a", "b") rdd.map{a => val aa = testList(0) None} However after declaring a custom dataframe type as proposed here //DATAFRAME EXTENSION import org.apache.spark.sql.DataFrame object ExtraDataFrameOperations { implicit class DFWithExtraOperations(df : DataFrame) { /