Undefined function 'solveVdp' for input arguments of type 'double' from Plot During Parameter Sweep with parfor

Running R2019A with Parallel toolbox and I'm testing it using fthe parfor tutorial. How do i get the solveVdp file to be available?

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>> D = parallel.pool.DataQueue;
D.afterEach(@(x) updateSurface(c, x));
>> parfor ii = 1:numel(N)
    [t, y] = solveVdp(N(ii), M(ii));
    l = islocalmax(y(:, 2));
    send(D, [ii mean(diff(t(l)))]);
end
Starting parallel pool (parpool) using the 'local' profile ...
Warning: The system time zone setting, 'US/Eastern', does not specify a single time
zone unambiguously. It will be treated as 'America/New_York'. See the
datetime.TimeZone property for details about specifying time zones. 
> In verifyTimeZone (line 34)
  In datetime (line 543)
  In parallel.internal.cluster.FileSerializer>iLoadDate (line 342)
  In parallel.internal.cluster.FileSerializer/getFields (line 100)
  In parallel.internal.cluster.CJSSupport/getProperties (line 260)
  In parallel.internal.cluster.CJSSupport/getJobProperties (line 491)
  In parallel.internal.cluster.CJSJobMixin/hGetProperty (line 108)
  In parallel.internal.cluster.CJSJobMethods.setJobTerminalStateFromCluster (line 179)
  In parallel.internal.cluster.CJSJobMixin/hSetTerminalStateFromCluster (line 160)
  In parallel.cluster.CJSCluster/hGetJobState (line 411)
  In parallel.internal.cluster.CJSJobMixin/hGetStateEnum (line 144)
  In parallel.Job/get.StateEnum (line 238)
  In parallel.Job/get.State (line 230)
  In parallel.internal.customattr.CustomGetSet>iVectorisedGetHelper (line 130)
  In parallel.internal.customattr.CustomGetSet>@(a,b,c)iVectorisedGetHelper(obj,a,b,c) (line 102)
  In parallel.internal.customattr.CustomGetSet/doVectorisedGet (line 103)
  In parallel.internal.customattr.CustomGetSet/hVectorisedGet (line 76)
  In parallel.internal.customattr.GetSetImpl>iAccessProperties (line 322)
  In parallel.internal.customattr.GetSetImpl>iGetAllProperties (line 283)
  In parallel.internal.customattr.GetSetImpl.getImpl (line 148)
  In parallel.internal.customattr.CustomGetSet/get (line 40)
  In parallel.internal.pool.InteractiveClient/pRemoveOldJobs (line 476)
  In parallel.internal.pool.InteractiveClient/start (line 317)
  In parallel.Pool>iStartClient (line 796)
  In parallel.Pool.hBuildPool (line 585)
  In parallel.internal.pool.doParpool (line 18)
  In parpool (line 98)
  In parallel.internal.pool.PoolArrayManager.getOrAutoCreateWithCleanup (line 60)
  In pctTryCreatePoolIfNecessary (line 23)
  In parallel_function 
Connected to the parallel pool (number of workers: 12).
Analyzing and transferring files to the workers ...done.
An UndefinedFunction error was thrown on the workers for 'solveVdp'.  This might be
because the file containing 'solveVdp' is not accessible on the workers.  Use
addAttachedFiles(pool, files) to specify the required files to be attached.  For
more information see the documentation for 'parallel.Pool/addAttachedFiles'.
Caused by:
    Undefined function 'solveVdp' for input arguments of type 'double'..