Can vpasolver work in simulink model?

Hello to everyone,

I wanted to create a function block on simulink with outputs calculated from the solution of vpasolver. When I run the simulink model I get an error saying

"Function 'syms' not supported for code generation. Function 'MATLAB Function' (#35.101.118), line 3, column 1: "syms Qp cp Qb cb" Launch diagnostic report."

Does this mean that vpasolver can't work on simulink? If yes, could there be a way to use it? Beneath it's the function I'm referring to.

Best regards,

Paris

function [Qp,cp,Qb,cb] = fcn(Q_in,c_in,r,P,i,T)
R = 0.0832; % Universal gas constant [L*atm/(K*mol)]
syms Qp cp Qb cb
S = vpasolve(r == 1-cp/c_in, Q_in == Qp+Qb, Q_in*c_in == Qp*cp + Qb*cb, P/(i*R*(T+273.15)) == cb-cp, [Qp cp Qb cb]);
Qp = S.Qp;
cp = S.cp;
Qb = S.Qb;
cb = S.cb;

Answer 1

[Uday Pradhan]

Hi,

I think a possible workaround to this would be to do the symbolic computations in a separte function script and call that function from your block as an extrinsic function. Example: Define 'fcn.m' that contains all the computations:

function [qp,cp,qb,cb] = fcn(Q_in,c_in,r,P,i,T)
R = 0.0832; % Universal gas constant [L*atm/(K*mol)]
syms Qp cp Qb cb
S = vpasolve(r == 1-cp/c_in, Q_in == Qp+Qb, Q_in*c_in == Qp*cp + Qb*cb, P/(i*R*(T+273.15)) == cb-cp, [Qp cp Qb cb]);
qp = double(S.Qp);
cp = double(S.cp);
qb = double(S.Qb);
cb = double(S.cb);
end

Then in the MATLAB function block call:

function [Qp,cp,Qb,cb] = fcn1(Q_in,c_in,r,P,i,T)
coder.extrinsic('fcn');
Qp = 0;
cp = 0;
Qb = 0;
cb = 0;
[Qp,cp,Qb,cb] = fcn(Q_in,c_in,r,P,i,T);

I hope this helps!

[Paris Pasqualin]

Thanks for the answer!

[Gordon]

Hi, Did this method work I can't seem to get it to work.

[Gordon]

I get the error that numvars = 0. So it's as if still not evaluating variables.

[Paris Pasqualin]

Hi Gordon,

You actually do not need the vpasolve for simulink. You run the vpasolve once without spacifing any of the parameters and you should get equations that correlate the output parameters with the input ones. In my case I have:

Cp1 = (Cf*(156250*A1*Ps + 156250*A1*Lp*P - 156250*A1*Lp*P*sigma - 13*Cf*Lp*T*i1*sigma + 13*Cf*Lp*T*i1*sigma^2))/(13*Cf*Lp*T*i1*sigma^2 - 13*Cf*Lp*T*i1*sigma + 156250*A1*Ps) - (24414062500*A1^2*Ps^2 - 317382812500*A1*Ps*((A1^2*Lp^2*P^2)/169 + (2*A1^2*Lp*P*Ps)/169 + (A1^2*Ps^2)/169 - (A1*Cf*Lp^2*P*T*i1*sigma^2)/1015625 + (A1*Cf*Lp*Ps*T*i1*sigma^2)/1015625 + (Cf^2*Lp^2*T^2*i1^2*sigma^4)/24414062500)^(1/2) + 24414062500*A1^2*Lp*P*Ps - 169*Cf^2*Lp^2*T^2*i1^2*sigma^3 + 169*Cf^2*Lp^2*T^2*i1^2*sigma^4 + 26406250*Cf*Lp*T*i1*sigma*((A1^2*Lp^2*P^2)/169 + (2*A1^2*Lp*P*Ps)/169 + (A1^2*Ps^2)/169 - (A1*Cf*Lp^2*P*T*i1*sigma^2)/1015625 + (A1*Cf*Lp*Ps*T*i1*sigma^2)/1015625 + (Cf^2*Lp^2*T^2*i1^2*sigma^4)/24414062500)^(1/2) - 26406250*Cf*Lp*T*i1*sigma^2*((A1^2*Lp^2*P^2)/169 + (2*A1^2*Lp*P*Ps)/169 + (A1^2*Ps^2)/169 - (A1*Cf*Lp^2*P*T*i1*sigma^2)/1015625 + (A1*Cf*Lp*Ps*T*i1*sigma^2)/1015625 + (Cf^2*Lp^2*T^2*i1^2*sigma^4)/24414062500)^(1/2) + 2031250*A1*Cf*Lp^2*P*T*i1*sigma + 4062500*A1*Cf*Lp*Ps*T*i1*sigma^2 - 2031250*A1*Cf*Lp^2*P*T*i1*sigma^2 - 2031250*A1*Cf*Lp*Ps*T*i1*sigma)/(26*Lp*T*i1*sigma*(13*Cf*Lp*T*i1*sigma^2 - 13*Cf*Lp*T*i1*sigma + 156250*A1*Ps));

Cp2 = (Cf*(156250*A1*Ps + 156250*A1*Lp*P - 156250*A1*Lp*P*sigma - 13*Cf*Lp*T*i1*sigma + 13*Cf*Lp*T*i1*sigma^2))/(13*Cf*Lp*T*i1*sigma^2 - 13*Cf*Lp*T*i1*sigma + 156250*A1*Ps) - (24414062500*A1^2*Ps^2 + 317382812500*A1*Ps*((A1^2*Lp^2*P^2)/169 + (2*A1^2*Lp*P*Ps)/169 + (A1^2*Ps^2)/169 - (A1*Cf*Lp^2*P*T*i1*sigma^2)/1015625 + (A1*Cf*Lp*Ps*T*i1*sigma^2)/1015625 + (Cf^2*Lp^2*T^2*i1^2*sigma^4)/24414062500)^(1/2) + 24414062500*A1^2*Lp*P*Ps - 169*Cf^2*Lp^2*T^2*i1^2*sigma^3 + 169*Cf^2*Lp^2*T^2*i1^2*sigma^4 - 26406250*Cf*Lp*T*i1*sigma*((A1^2*Lp^2*P^2)/169 + (2*A1^2*Lp*P*Ps)/169 + (A1^2*Ps^2)/169 - (A1*Cf*Lp^2*P*T*i1*sigma^2)/1015625 + (A1*Cf*Lp*Ps*T*i1*sigma^2)/1015625 + (Cf^2*Lp^2*T^2*i1^2*sigma^4)/24414062500)^(1/2) + 26406250*Cf*Lp*T*i1*sigma^2*((A1^2*Lp^2*P^2)/169 + (2*A1^2*Lp*P*Ps)/169 + (A1^2*Ps^2)/169 - (A1*Cf*Lp^2*P*T*i1*sigma^2)/1015625 + (A1*Cf*Lp*Ps*T*i1*sigma^2)/1015625 + (Cf^2*Lp^2*T^2*i1^2*sigma^4)/24414062500)^(1/2) + 2031250*A1*Cf*Lp^2*P*T*i1*sigma + 4062500*A1*Cf*Lp*Ps*T*i1*sigma^2 - 2031250*A1*Cf*Lp^2*P*T*i1*sigma^2 - 2031250*A1*Cf*Lp*Ps*T*i1*sigma)/(26*Lp*T*i1*sigma*(13*Cf*Lp*T*i1*sigma^2 - 13*Cf*Lp*T*i1*sigma + 156250*A1*Ps));

Then you use these equations in simulink.

Kind regards,

Paris