The evaluation mechanism in Haskell is by-need: when a value is needed, it is calculated, and kept ready in case it is asked for again. If we define some list, xs=[0..] and later ask for its 100th element, xs!!99, the 100th slot in the list gets “fleshed out”, holding the number 99 now, ready for … Read more
Following from Pillsy’s reference to matrix exponentiation, such that for the matrix M = [1 1] [1 0] then fib(n) = Mn1,2 Raising matrices to powers using repeated multiplication is not very efficient. Two approaches to matrix exponentiation are divide and conquer which yields Mn in O(ln n) steps, or eigenvalue decomposition which is constant … Read more
How to write a trait bound for adding two references of a generic type? Let’s start with a simplified example: fn add_things<T>(a: &T, b: &T) { a + b; } This has the error error[E0369]: binary operation `+` cannot be applied to type `&T` –> src/lib.rs:2:5 | 2 | a + b; | ^^^^^ | … Read more
How to write the Fibonacci Sequence?
You model the time function to calculate Fib(n) as sum of time to calculate Fib(n-1) plus the time to calculate Fib(n-2) plus the time to add them together (O(1)). This is assuming that repeated evaluations of the same Fib(n) take the same time – i.e. no memoization is used. T(n<=1) = O(1) T(n) = T(n-1) … Read more
UPDATE: Try following one. Parameters: n from where to start saving numbers, m how many numbers do you want to save function getFibonacci(n,m) { var a = 0, b = 1, z = null, arr = [], c = 0; for ( var i = 0; i <= n; i++ ) { if ( a … Read more
int n, fibs[n]; attempts to define an array using n for the length, but n has not been initialized, so its value is not determined. Common consequences include: The definition behaves as if n has some small value, possibly zero, and then the following code attempts to store values in the array but overruns the … Read more