dot indexing not supported by variable of this type

function [lon, lat, h] = Geodetic(r)

global const

R_equ = const.R_Earth;

f = const.f_Earth;

epsRequ = eps*R_equ; % Convergence criterion

e2 = f*(2-f); % Square of eccentricity

X = r(1); % Cartesian coordinates

Y = r(2);

Z = r(3);

rho2 = X*X + Y*Y; % Square of distance from z-axis

% Check validity of input data

if (norm(r)==0)

disp ( ' invalid input in Geodetic constructor\n' );

lon = 0;

lat = 0;

h = -const.R_Earth;

return

end

% Iteration

dZ = e2*Z;

while(1)

ZdZ = Z + dZ;

Nh = sqrt ( rho2 + ZdZ*ZdZ );

SinPhi = ZdZ / Nh; % Sine of geodetic latitude

N = R_equ / sqrt(1-e2*SinPhi*SinPhi);

dZ_new = N*e2*SinPhi;

if (abs(dZ-dZ_new) < epsRequ)

break

end

dZ = dZ_new;

end

% Longitude, latitude, altitude

lon = atan2(Y, X);

lat = atan2(ZdZ, sqrt(rho2));

h = Nh - N;

Dot indexing is not supported for variables of this type.

Error in Geodetic (line 13)

R_equ = const.R_Earth;

Answer 1

[Arthur Roué]

Your variable const is a global one. First of all, use of global variables is widely not reccomended, read this article for more details : https://fr.mathworks.com/help/matlab/matlab_prog/share-data-between-workspaces.html.

Then, if your global variable const is not defined (e.g. first call of your function), the line

global const

will initialize it with an empty double. Then you have to initialize it as a struct if you want to call it this way (with dot indexing).

global const

if isempty(const)
    const = struct('R_Earth', yourVal, 'f_Earth', yourVal)
end

[Arthur Roué]

Did it work for you ?