How to resolve the algorithm Pascal's triangle step by step in the Julia programming language
How to resolve the algorithm Pascal's triangle step by step in the Julia programming language
Table of Contents
Problem Statement
Pascal's triangle is an arithmetic and geometric figure often associated with the name of Blaise Pascal, but also studied centuries earlier in India, Persia, China and elsewhere. Its first few rows look like this: where each element of each row is either 1 or the sum of the two elements right above it. For example, the next row of the triangle would be: So the triangle now looks like this: Each row n (starting with row 0 at the top) shows the coefficients of the binomial expansion of (x + y)n.
Write a function that prints out the first n rows of the triangle (with f(1) yielding the row consisting of only the element 1). This can be done either by summing elements from the previous rows or using a binary coefficient or combination function. Behavior for n ≤ 0 does not need to be uniform, but should be noted.
Let's start with the solution:
Step by Step solution about How to resolve the algorithm Pascal's triangle step by step in the Julia programming language
The provided Julia code defines two functions named pascal
to generate and print Pascal's triangle. Here's a detailed explanation of both functions:
1. First pascal
function:
-
iround(x)
: This function converts a floating-point numberx
to its nearest rounded integer value of typeInt64
. -
triangle(n)
: This function generates the coefficients of the rows of Pascal's triangle up to rown
using a matrix exponential and returns them as an array of integers. -
pascal(n)
: This function prints the firstn
rows of Pascal's triangle using thetriangle
function and theprintln
function. It iterates through the rows from 1 ton+1
and prints the non-zero elements of each row, separated by spaces.
2. Second pascal
function:
-
pascal(n)
: This is an alternative implementation of the Pascal's triangle generation function. It takes a positive integern
as input. It checks ifn
is less than or equal to 0, and if so, it throws an error because Pascal's triangle cannot have zero or negative rows. -
The function initializes two vectors
r
andpr
withn
elements, both initially filled with undefined values. It then sets the first element of both vectors to 1. -
It enters a loop that iterates from
2
ton
. In each iteration, it updates the first element ofr
andpr
to 1. -
For each element in
r
from index 2 toi-1
, it updates the value by adding the corresponding elements frompr
. -
It prints the current row of Pascal's triangle by joining the elements of
r
from index 1 toi
using thejoin
function and separating them with spaces. -
Finally, it updates
r
andpr
by swapping their roles (r
becomespr
, andpr
becomesr
) and continues to the next iteration.
Source code in the julia programming language
iround(x) = round(Int64, x)
triangle(n) = iround.(exp(diagm(-1=> 1:n)))
function pascal(n)
t=triangle(n)
println.(join.([filter(!iszero, t[i,:]) for i in 1:(n+1)], " "))
end
function pascal(n)
(n<=0) && error("Pascal trinalge can not have zero or negative rows")
r=Vector{Int}(undef,n)
pr=Vector{Int}(undef,n)
pr[1]=r[1]=1
println(@view pr[1])
for i=2:n
r[1]=r[i]=1
for j=2:i-1
r[j]=pr[j-1]+pr[j]
end
println(join(view(r,1:i), " "))
r,pr=pr,r
end
end
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