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straypacket/wifi_math.rb

Last active August 29, 2015 13:57
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Linalg for wifi
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wifi_math.rb
require 'linalg'
include Linalg
# Linear equation to solve:
# a * x = b
#
# Example
# a = DMatrix[[1,0,0],[0,2,0],[0,0,1]]
# b = DMatrix[[1,1],[2,2],[3,3]]
#
# x = DMatrix.solve(a,b)
b = DMatrix[[2156,779],[2249,793],[2333,842],[2492,751],[2369,734],[2120,668],[2121,508],[2260,484],[2238,605],[2130,566],[2486,839],[2292,739],[2226,517]]
# We don't have "distances" between measurement points, but we can try to approximate them by the difference of powers
p = DMatrix[[38,27,41],[49,31,37],[45,43,30],[43,40,27],[45,36,32],[27,27,43],[29,36,41],[23,40,54],[33,36,47],[34,43,36],[53,38,15],[46,28,35],[28,36,52]]
pr = p.rows.count
a = DMatrix.new(pr,pr)
0.upto(pr-1) { |x| 0.upto(pr-1) { |y| a[x,y] = ((p[x,0]-p[y,0])**2 + (p[x,1]-p[y,1])**2 + (p[x,2]-p[y,2])**2)**0.5 } }
# Solve equations
x = DMatrix.solve(a,b)
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