Why is the function "distance" not supported for code generation in MATLAB R2025b?

I’m trying to use the Mapping Toolbox function distance in a MATLAB Function block within a Simulink model that will be compiled into a shared object. I encountered the error:

Function 'distance' not supported for code generation. 

Is there another approach or function I can use to achieve the same functionality? 

Answer 1

[MathWorks Support Team]

This distance function from the Mapping Toolbox is not currently supported for code generation in MATLAB R2025b.

To achieve the desired functionality, please consider the following approaches:

1. 

Write Formula Manually Into the MATLAB Function Block:

Below is an example implementation that is supported for code generation. Please test and adapt it to ensure it meets your application’s needs before implementing it:

function [arclen, az] = sphericalDistance(lat1, lon1, lat2, lon2)
%#codegen
% Inputs in degrees, outputs in degrees

% Convert to radians
lat1 = deg2rad(lat1);
lon1 = deg2rad(lon1);
lat2 = deg2rad(lat2);
lon2 = deg2rad(lon2);

% Compute angular distance using spherical law of cosines
delta_lon = lon2 - lon1;
cos_arclen = sin(lat1)*sin(lat2) + cos(lat1)*cos(lat2)*cos(delta_lon);
cos_arclen = min(max(cos_arclen, -1), 1); % Clamp for numerical stability
arclen_rad = acos(cos_arclen);
arclen = rad2deg(arclen_rad);

% Compute azimuth (initial bearing)
y = sin(delta_lon) * cos(lat2);
x = cos(lat1)*sin(lat2) - sin(lat1)*cos(lat2)*cos(delta_lon);
az_rad = atan2(y, x);
az = mod(rad2deg(az_rad), 360); % Normalize to [0, 360)
end

2. Precompute Outputs and Use Lookup Table: If your inputs to the distance function are fixed or change infrequently, you might consider precomputing the outputs and using a lookup table in Simulink.

3. 

Develop C Implementation:

If you have access to a C implementation of the distance function, you could

integrate a function that is not supported for code generation

using "coder.ceval".