fizzbuzz/hotplate.js

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/*
* Weds Oct 20th 2010
*
* Helping a friend with some homework, decided to do it for myself for fun.
*
* CS142 - BYU Fall Semester 2010 - Hotplate Lab
*
* The spec is like this:
*
* use a 2-d array representing a (18x18) plate with 4 edges (20x20 total) touching
* two sides against a maximum (100) temperature surface (the first and last rows)
* and the others against a minimum (0) temperature surface (the first and last columns)
*
* Each instant the temperature of a given point on the plate (hotplate[x][y])
* is calculated by averaging the top, bottom, left, and right points onto
* the point itself.
*
* Find the number of instances it takes until the difference between the previous
* and current temperature of the point which has changed the most in temperature
* is less than 0.1 units.
*
* Output the temperature of each point during that instant as a CSV.
* View the results in a spreadsheet.
*
*/
var HotPlate = {};
(function () {
var hotplate = [
[ 0, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 0 ]
];
// This is code I used to generate the array above (with a few minor modifications)
/*
var result = "[\n", i, j;
result += '[';
for (j = 0; j < 20; j += 1) {
result += '100, ';
}
result += '],\n';
for (i = 2; i < 20; i += 1) {
result += '[';
for (j = 0; j < 20; j += 1) {
result += ' 0, ';
}
result += '],\n';
}
result += '[';
for (j = 0; j < 20; j += 1) {
result += '100, ';
}
result += '],\n';
result += ']\n';
console.log(result);
*/
function find_steady_state_temperature() {
var row,
column,
sum, // the sum of surrounding cells
original, // the value of a cell before the change
variance, // the max of all the variances
allowed_variance = 0.1, // how much any cell may vary in temperature from one instance to the next.
// 0.000000000000001 is the lowest you can go. If you try zero it will run forever (IEEE floating-point errors?)
repeat = true, // if the base condition has yet to be met
count = 0, // safeguard in case the base-case logic is incorrect
max_count = 15000;
while (true === repeat && count < max_count) {
variance = 0;
for (row = 1; row < 19; row += 1) {
for (column = 1; column < 19; column += 1) {
original = hotplate[row][column];
sum = 0;
sum += hotplate[row-1][column];
sum += hotplate[row][column-1];
sum += hotplate[row+1][column];
sum += hotplate[row][column+1];
hotplate[row][column] = sum / 4;
variance = Math.max(hotplate[row][column] - original, variance);
}
}
repeat = variance >= allowed_variance;
count += 1;
}
if (max_count === count) {
console.log("EPIC FAIL");
} else {
console.log("SUCCESS in just " + count + " instances!");
}
}
function inspect() {
var result = '', str = '';
for (i = 0; i < 20; i += 1) {
for (j = 0; j < 20; j += 1) {
str = hotplate[i][j].toFixed(1).toString();
while (str.length < 5) {
str = ' ' + str;
}
str += ', ';
result += str;
}
result += '\n';
}
console.log(result);
}
HotPlate.inspect = inspect;
HotPlate.calculate_steady_state_temperature = find_steady_state_temperature;
}());
HotPlate.calculate_steady_state_temperature();
HotPlate.inspect();