"One or more output arguments not assigned during call to "varargout""

Hi everyone,

I'm currently working with a complex model that contains many interconnected functions.

1) At some point, I call the function rk4.m:

[TS.T, rk1_T, V1T, H1T, X1T, rk2_T, V2T, H2T, X2T, rk3_T, V3T, H3T, X3T, rk4_T, V4T, H4T, X4T, srf_Tflx1, sol_Tflx1, srf_Tflx2, sol_Tflx2, srf_Tflx3, sol_Tflx3, srf_Tflx4,...
    sol_Tflx4] = rk4(@mixtracerTS_ode, it, TS.T, In, Grd, VMxng.Mld, VMxng.Entrnmnt, LB.tmp, TS.Sig, Wnd.Tauy2, P, 'sflux', Ht.Qi, Ht.airtmp, Ht.dewptT, Wnd.Wspd10,...
    Ht.Qo,'source',Ht.Qi);

rk4.m is defined as follows:

function [y1, k_1, V1, H1, X1, k_2, V2, H2, X2, k_3, V3, H3, X3, k_4, V4, H4, X4, varargout] = rk4(ode, it, y0, In, Grd, varargin)

2) Inside rk4.m, I call several times the function ode / mixtracerTS_ode.m. For instance, the first time:

[k_1, V1, H1, X1, srf_Tflx1, sol_Tflx1] = ode(Grd.time(it), y0, In, Grd, varargin {:});

mixtracerTS_ode.m is defined as follows:

    function [dxdt, V, H, X, varargout] = mixtracerTS_ode(time, tracer, In, Grd, mld, ent, lb, Sig, tauy, prate, varargin)

a) mandatory output arguments are calculated thanks to other functions:

        V = verticalmixing(tracer, Grd, mld, ent, In, time);
        H = horizontalmixing(tracer, Grd, mld, lb, In, time);
        X = advection(tracer, lb, In, Grd, mld, tauy, Sig, prate, time);
        dxdt = V+ H+ X;

b) portion to calculate varargout / srf_Tflx1 & sol_Tflx1:

         nArgs=length(varargin);
         if nArgs >0
         opt = varargin(cellfun(@ischar,varargin));
         if any(ismember(opt, {'sflux'}))      
         Ht.Qi=varargin{2};
         Ht.airtmp=varargin{3};
         Ht.dewptT=varargin{4};
         Wnd.Wspd10=varargin{5};
         Ht.Qo=varargin{6};
         .......
         .......
         calculation of srf_Tflx
         ......
         varargout{1}=srf_Tflx;
         end
         opt = varargin(cellfun(@ischar,varargin));
         if any(ismember(opt, {'source'}))        
         Ht.Qi=varargin{8};
         ......
         ......
         calculation of sol_Tflx
         .......
         .......
         varargout{2}=sol_Tflx;
         end
         end

I get this error message:

One or more output arguments not assigned during call to "varargout"
Error in rk4 (line 39)
[k_1, V1, H1, X1, srf_Tflx1, sol_Tflx1] = ode(x(it), y0, In, Grd, varargin {:});

I really can't figure this out especially because everything works fine when I run my functions from the command window with appropriate inputs!! For example, the first function to be called

[TS.T, rk1_T,......, sol_Tflx4]=rk4(@mixtracerTS_ode, .... , Ht.Qi) gives me the expected outputs. But when I run the entire model, I get the above error message.

Any help from you would be much appreciated !!

Many thanks in advance.

[Walter Roberson]

I think we may need the full code to test with.

[Virginie Bornarel]

Hi Walter,

You can get the full code there:

https://github.com/virginie01/WCVI-E2E

Just create a folder (for ex WCVI-E2E) and transfer mergestruct, physical_model, seawater_ver3_2, debug.mat, and mixedlayer_examples.m into it.

You can run the entire model by opening mixedlayer_examples.m and only running lines 9-11 (i.e. addpath...) and then line 40 to run the model (i.e. WCVIE2E_physicalmodel('default','Tdiag',true,'Sdiag',true). Disregard the rest.

The key functions to look into are WCVIE2E_physical model.m (line378-386), rk4.m, and mixtracerTS_ode.m.

If you wanna run some of these functions from the command window to see that it works fine, you can download debug.mat that contains the appropriate inputs to run line 378-382 of WCVIE2E_physicalmodel.m

Thank you so much for your help ! Hugely grateful !

[Guillaume]

I've not looked at the code yet, but the error message seem to says that matlab thinks that you've got a function called varargout. Have you checked that you've got no such function hidden somewhere?

Looking just at the snippet you've posted above, something is a bit iffy without varargin parsing. I doubt it is related to your error though. You do

opt = varargin(cellfun(@ischar,varargin));
if any(ismember(opt, {'sflux'}))

so this allows passing 'sflux' as any element of varargin. Yet, you have then

Ht.Qi=varargin{2};
Ht.airtmp=varargin{3};
Ht.dewptT=varargin{4};
Wnd.Wspd10=varargin{5};
Ht.Qo=varargin{6};

which has the positions of all inputs hardcoded and implies 'sflux' must be passed as the first argument. So really, that first bit should be:

if ischar(varargin{1}) && strcmp(varargin{1}, 'sflux')

or the 2nd bit should be relative to the position of 'sflux'.

Same for 'source'

[Virginie Bornarel]

Thanks for your help Guillaume. I'll try this alternative but 'sflux' is passed as the first argument so not sure this will solve the problem. But gonna try this ;)

Answer 1

[Walter Roberson]

rk4 line 39, you always call ode with 6 outputs, but the inputs can vary because of the varargin{:}

WCVOE2E_physicalmodel, line 378, you call rk4 passing in both 'source' and 'sflux' options and expecting 25 outputs.

Line 384, you call rk4 without 'source' or 'sflux' options and expecting 17 outputs.

mixtracerTS_ode line 1 defines 4 constant outputs and varargout. With it being called by rk4 with 6 outputs each time, varargout{1} and varargout{2} will need to be set each time.

mixtracerTS_ode.m lines 82-83 checks nargin . In both calls (line 378 vs line 384) nargin is non-empty, so 'sflux' is checked for. The call on line 378 (the first call) provided it so the if on line 86 of mixtracerTS_ode.m gets control and assigns to varargout{1} on line 122; similarly with 'source' having been passed, the if on line 132 has control and assigns to varargout{2} on line 174. But the call on line 384 (the second call) provided neither sflux nor source, so the assignments at line 122 and 174 are not executed, and varargout{1} and varargout{2} are not assigned to, leaving you two outputs short for the call to ode() on line 39 of rk4.

[Virginie Bornarel]

Hi Walter,

I don't always call ode with 6 outputs in rk4.m. I do call ode with 4 outputs (see lines 55-58 of rk4.m). In rk4.m, the number of inputs vary with varargin{:} indeed. But I make sure that I call ode with 6 outputs in rk4.m only when I call rk4 passing in both 'source' and 'sflux' options in WCVIE2E_physicalmodel.m. I do that by adding lines 35 and 37 in rk4.m:

opt = varargin(cellfun(@ischar,varargin));

if all(ismember(opt, {'sflux','source'})).

So everything should match right?

More generally, if there was an error, why am I still able to run the line 378 of WCVIE2E_physicalmodel.m from the command window when I use appropriate inputs (the ones in debug.mat)???

[Walter Roberson]

When ischar is not true for any entry in varargin, then the cellfun() returns empty, and varargin(empty) returns empty. ismember(empty, something) returns empty, all(empty) returns true.

You are probably expecting that the all() returns false under that circumstance.

[Virginie Bornarel]

Thank you Walter!!

Replaced

opt = varargin(cellfun(@ischar,varargin));

if all(ismember(opt, {'sflux','source'})).

by:

if any(cellfun(@ischar,varargin)).

The error message doesn't pop up anymore ... :)