tempCodeRunnerFile.julia

import math
import numpy

#assuming elevation = 0
earthR = 6371
LatA = 37.418436
LonA = -121.963477
DistA = 0.265710701754
LatB = 37.417243
LonB = -121.961889
DistB = 0.234592423446
LatC = 37.418692
LonC = -121.960194
DistC = 0.0548954278262

#using authalic sphere
#if using an ellipsoid this step is slightly different
#Convert geodetic Lat/Long to ECEF xyz
#   1. Convert Lat/Long to radians
#   2. Convert Lat/Long(radians) to ECEF
xA = earthR *(math.cos(math.radians(LatA)) * math.cos(math.radians(LonA)))
yA = earthR *(math.cos(math.radians(LatA)) * math.sin(math.radians(LonA)))
zA = earthR *(math.sin(math.radians(LatA)))

xB = earthR *(math.cos(math.radians(LatB)) * math.cos(math.radians(LonB)))
yB = earthR *(math.cos(math.radians(LatB)) * math.sin(math.radians(LonB)))
zB = earthR *(math.sin(math.radians(LatB)))

xC = earthR *(math.cos(math.radians(LatC)) * math.cos(math.radians(LonC)))
yC = earthR *(math.cos(math.radians(LatC)) * math.sin(math.radians(LonC)))
zC = earthR *(math.sin(math.radians(LatC)))

P1 = numpy.array([xA, yA, zA])
P2 = numpy.array([xB, yB, zB])
P3 = numpy.array([xC, yC, zC])

#from wikipedia
#transform to get circle 1 at origin
#transform to get circle 2 on x axis
ex = (P2 - P1)/(numpy.linalg.norm(P2 - P1))
i = numpy.dot(ex, P3 - P1)
ey = (P3 - P1 - i*ex)/(numpy.linalg.norm(P3 - P1 - i*ex))
ez = numpy.cross(ex,ey)
d = numpy.linalg.norm(P2 - P1)
j = numpy.dot(ey, P3 - P1)

#from wikipedia
#plug and chug using above values
x = (pow(DistA,2) - pow(DistB,2) + pow(d,2))/(2*d)
y = ((pow(DistA,2) - pow(DistC,2) + pow(i,2) + pow(j,2))/(2*j)) - ((i/j)*x)

# only one case shown here
z = numpy.sqrt(pow(DistA,2) - pow(x,2) - pow(y,2))

#triPt is an array with ECEF x,y,z of trilateration point
triPt = P1 + x*ex + y*ey + z*ez

#convert back to lat/long from ECEF
#convert to degrees
lat = math.degrees(math.asin(triPt[2] / earthR))
lon = math.degrees(math.atan2(triPt[1],triPt[0]))

print (lat, lon)