save() seems to be saving objects that should be destroyed, causing errors when the resulting .mat file is loaded

Example code:

txs = txsite("AntennaHeight",1.5, ...
            "Latitude", 38.9899587, "Longitude", -76.9353889, ...
            "TransmitterPower", 10);
rxs = rxsite("AntennaHeight", 1.5, ...
            "Latitude", 38.9860195, "Longitude", -76.9412203);
pm = propagationModel('raytracing');
rays = raytrace(txs, rxs, pm, "type", "power"); % rays is Na x Ns cell array

if ~isempty(rays{1}) % only ever 1 tx/1 rx
    rayPower = 0;
    % phasor sum of rec'd power
    for rayPath = 1:numel(rays{1})
        pWatts = 10^(-rays{1}(rayPath).PathLoss/10)*10;
        rayPower = rayPower + pWatts*(cos(rays{1}(rayPath).PhaseShift) + 1i*sin(rays{1}(rayPath).PhaseShift));
    end
    % convert to RSS in dBm and resultant signal phase offset
    RSS = 10*log10(abs(rayPower)/.001); % dBm
    phaseOffset = angle(rayPower) ; % rads
    % collate data
    data = [RSS, phaseOffset];
end
close all force % this is an attempt to fix this issue
save("data.mat","data")

The above code works as expected however, running:

load("data.mat")

Will result in the following warnings being spammed in the console:

> In <FUNCTION> (line 25) 
Warning: Unable to load C++ object. Saving (serializing) C++ objects into a MAT-file is not supported. 
> In <FUNCTION> (line 25) 
Warning: Cannot load an object of class 'proplistener':
 No matching constructor signature found. 
> In <FUNCTION> (line 25) 
Warning: During load:
 An invalid default object has been detected while loading a heterogeneous array of class event.proplistener. An empty array of
 class event.proplistener will be returned. 
> In <FUNCTION> (line 25) 
Warning: While loading an object of class 'siteviewer':
Unrecognized field name "Name".

I thought foriclby closing the siteviewer would work (or at least get rid of the last error), but it has not seemed to have an effect. What command should I run to fix this behavior?

Tested on 2023b, 2024b and the 2025 prerelease across two computers (one Win10, one Ubuntu22) which both had similar behaviors, although the Windows mahcine produced far fewer warnings.

[Sandeep Mishra]

Hi @Alex B

Could you please provide details for the variables 'pm', 'samplePoints', and 'step' for better debugging?

[Alex B]

Made some edits to the code, forgot to remove those when I pasted from a much larger file.

I am certain this particular loop is what causing my issue though, as the larger file just contains logic to run this data collection step many times.

[Fangjun Jiang]

Can you press the "RUN" button in your example code section? "rxs" is not defined

[Alex B]

works now, line 3 shoudlve been rxs = rxsite(...)

Answer 1

[Alex B]

As an update on this I fixed everything except the "Unrecognized field name: Name" warning by just opening and saving the file again after creation. This issue also only seems to occur on files created using my work (Ubuntu) comptuer, my personal (Windows) computer does not do this. I am still not sure what bad objects it was attempting to save.

Unfortunately, it seems like the final error can only be fixed by specifying the site name when the data is created - attempting to do something like:

site = siteviewer()

site.Name = "Test"

save("test.mat",site)

load("test.mat")

Will result in the warning:

Warning: While loading an object of class 'siteviewer':

Dot indexing is not supported for variables of this type.

when saving or loading the respecitve file.

Edit:

Also, upon clearing the variable scen you will get:

Warning: The following error was caught while executing 'matlab.internal.asynchttpsave.AsyncHTTPContentFileWriter' class destructor:

Output argument "result" (and possibly others) not assigned a value in the execution with "matlabshared.asyncio.internal/Channel/isOpen" function.

Error in matlab.internal.asynchttpsave.AsyncHTTPContentFileWriter/cancelAndCloseChannel

Error in matlab.internal.asynchttpsave.AsyncHTTPContentFileWriter/delete

Answer 2

[Steven Lord]

txs = txsite("AntennaHeight",1.5, ...
            "Latitude", 38.9899587, "Longitude", -76.9353889, ...
            "TransmitterPower", 10);

When I ran the raytrace function it complained that the variable rxs was unrecognized. Since you defined a variable txs twice, I'm assuming the second one was supposed to be rxs and use rxsite instead of txsite.

rxs = rxsite("AntennaHeight", 1.5, ...
            "Latitude", 38.9860195, "Longitude", -76.9412203);
pm = propagationModel('raytracing');
rays = raytrace(txs, rxs, pm, "type", "power"); % rays is Na x Ns cell array
if ~isempty(rays{1}) % only ever 1 tx/1 rx
    rayPower = 0;
    % phasor sum of rec'd power
    for rayPath = 1:numel(rays{1})
        pWatts = 10^(-rays{1}(rayPath).PathLoss/10)*10;
        rayPower = rayPower + pWatts*(cos(rays{1}(rayPath).PhaseShift) + 1i*sin(rays{1}(rayPath).PhaseShift));
    end
    % convert to RSS in dBm and resultant signal phase offset
    RSS = 10*log10(abs(rayPower)/.001); % dBm
    phaseOffset = angle(rayPower) ; % rads
    % collate data
    data = [RSS, phaseOffset];
end

Let's see what variables are in the workspace right now.

whos

  Name             Size            Bytes  Class                Attributes

  RSS              1x1                 8  double                         
  data             1x2                16  double                         
  pWatts           1x1                 8  double                         
  phaseOffset      1x1                 8  double                         
  pm               1x1              1250  rfprop.RayTracing              
  rayPath          1x1                 8  double                         
  rayPower         1x1                16  double               complex   
  rays             1x1              2632  cell                           
  rxs              1x1                 8  rxsite                         
  txs              1x1                 8  txsite                         

Now we can save the data variable and try to reload it.

cd(tempdir)
save("data.mat", "data")
whos -file data.mat % check which variable are in the MAT-file

  Name      Size            Bytes  Class     Attributes

  data      1x2                16  double              

clear data % Get rid of the variable from the workspace
load("data.mat") % Load it back in again
whos

  Name             Size            Bytes  Class                Attributes

  RSS              1x1                 8  double                         
  data             1x2                16  double                         
  pWatts           1x1                 8  double                         
  phaseOffset      1x1                 8  double                         
  pm               1x1              1250  rfprop.RayTracing              
  rayPath          1x1                 8  double                         
  rayPower         1x1                16  double               complex   
  rays             1x1              2632  cell                           
  rxs              1x1                 8  rxsite                         
  txs              1x1                 8  txsite                         

Since there's no warnings issued by this load call, there must be something different about the actual code you're running from what you posted. Did you perhaps call save with just the name of the MAT-file to be saved?

save("data2.mat")
load("data2.mat") % No warnings
clear all
load("data2.mat") % Still no warnings

I think you're going to need to show us the body of your <FUNCTION> function.

[Alex B]

Relevant open street map can be found here; the site won't let me upload .osm files.