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Title	Ulam Spiral Fun
ID	956488031
Created	13 years ago, 1353002732994
Updated	13 years ago, 1344639118044
Code	var cellSize = 17; //set the cell size var circleScale = 1.2; //scale of each circle relative to cell //make sure cell size doesn't get too small cellSize = max(3, cellSize); //find the total number of cells in each direction var xCells = round(400 / cellSize) + 1; //added one in previous line to make sure that we fill the canvas var yCells = xCells; //we need the same number of cells in the x and y directions //initialize 2-dimensional array that holds the cell values var cellArray = []; for(var i = 0; i < xCells + 1; i++) { cellArray[i] = []; } //calculate the "center" cell in the matrix var curCellX = round(xCells / 2); var curCellY = round(yCells / 2); //determines the direction we are traveling in as we spiral var xDir = 1; var yDir = 0; //makes sure that the center cell exactly corressponds to the center of the canvas var offset = 200 - cellSize * curCellX; //determines the number of factors var numFactors = function(number) { if (number===1) { return 1; } var factorCount = 0; var sqrtNum = sqrt(number); for (var i = 1; i <= sqrtNum; i++) { if (number % i === 0) { factorCount++; } } if (number/round(sqrtNum)===sqrtNum) { return (2factorCount - 1); } else { return (2factorCount); } }; background(37, 48, 48); //fill in the values of the array in a spiral pattern var numCells = max(1, xCellsyCells); for (var number = 1; number < numCells; number ++) { var value = numFactors(number); cellArray[curCellX][curCellY] = value; //don't want to draw the boundaries of the circles if the cells are too small if (cellSize < 10) { noStroke(); } var r = cellSize/valuecircleScale; fill(255-255/r, 128-255/r, 200-255/r); ellipse(cellSizecurCellX+offset, cellSizecurCellY+offset, r,r); if (xDir === 1 && yDir === 0) { //going right if (!cellArray[curCellX][curCellY - 1]) { xDir = 0; yDir = -1; } } else if (xDir === 0 && yDir === -1) { //going up if (!cellArray[curCellX - 1][curCellY]) { xDir = -1; yDir = 0; } } else if (xDir === -1 && yDir === 0) { //going left if (!cellArray[curCellX][curCellY + 1]) { xDir = 0; yDir = 1; } } else { //going down if (!cellArray[curCellX + 1][curCellY]) { xDir = 1; yDir = 0; } } curCellX += xDir; curCellY += yDir; }
Folds
Fork	false
Key	ag5zfmtoYW4tYWNhZGVteXIUCxIKU2NyYXRjaHBhZBjfsovIAww
Votes	171
Spin-Offs	43
Type	PJS
Width	400
Height	400
User Flagged	false
Origin Scratchpad	null
Hidden From Hotlist	false
Restricted Posting	false
By Child	false
Author Nick	Sal Khan
Author Name	sal
Author ID	kaid_326465577260382527912172
Author Profile Access	COACH

Archive Data

Added	10 months ago, 1739361584373
Updated	10 months ago, 1739467949338
Source Deleted	unknown