You can write your own normpdf if that is all you need. Here it is as an anonymous function (see: https://www.originlab.com/doc/LabTalk/ref/Normpdf-func)
normpdf = @(x,mu,sigma) (1.0./(sqrt(2*pi).*sigma))*exp(-0.5*((x-mu)./sigma).^2);
GPS is typically referenced to the WGS84 Earth Ellipsoid. You can readily implement the algorithm outlined in the Geographic coordinate conversion - From geodetic to ECEF coordinates wikipedia page:
where Φ is latitude, λ is longitude, and
Use a site like this online calculator to spot verify your code (check the stressing points like poles, equator as well as some reference points: https://www.oc.nps.edu/oc2902w/coord/llhxyz.htm
This code needs some range checking and array checking to be robust:
function [x_m,y_m,z_m] = convLLA2ECEF(lat_degN,lon_degE,alt_m)
%% *purpose*
% convert WGS84 Lat, Lon, Alt to ECEF X, Y, Z
%% *inputs*
% lat_degN - [degrees North] latitude values
% lon_degE - [degrees East] longitude values
% alt_m - [m] height Above Mean Sea Level (WGS84 Ellipsoid Reference)
%% *outputs*
% x_m - [m] ECEF x values
% y_m - [m] ECEF y values
% z_m - [m] ECEF z values
%% *start*
WGS84_e2 = 6.69437999014e-3; % [unitless] square of WGS84 1st eccentricity
WGS84_a = 6378137.0; % [m] equatorial radius defined by WGS84 ellipsoid
clat = cosd(lat_degN);
slat = sind(lat_degN);
clon = cosd(lon_degE);
slon = sind(lon_degE);
N = WGS84_a ./ sqrt(1.0 - WGS84_e2 * slat .* slat);
x_m = (N + alt_m) .* clat .* clon;
y_m = (N + alt_m) .* clat .* slon;
z_m = (N .* (1.0 - WGS84_e2) + alt_m) .* slat;
return
end
