How to use root() and vpa() from symbolic math toolbox in simulink?

I have computed an analytical solution to a problem, using the symbolic math toolbox I can now solve the problem with the following MATLAB function

function y  = symbolicFunction(x0,x1,x2,x3,x4,x5)
syms z
y = vpa(root(z^6 - z^4*(- 300*x2*x5 + 450*x2^2 + 450*x5^2) - z^3*(7200*x2*x1 + 4800*x2*x4 - 4800*x5*x1 - 7200*x5*x4) - z^2*(18000*x2*x0 - 18000*x2*x3 - 18000*x5*x0 + 18000*x5*x3 + 50400*x1*x4 + 28800*x1^2 + 28800*x4^2) - z*(144000*x1*x0 - 144000*x1*x3 + 144000*x4*x0 - 144000*x4*x3) + 360000*x0*x3 - 180000*x3^2 - 180000*x0^2, z, 1));
end

I want to implement this solution in a simulink model, but I cannot directly add this function in simulink. The most important error states

Function 'syms' not supported for code generation.

I have tried:

• Trying to write the analytical solution such that it doesn't require the symbolic toolbox, but I didn't manage to achive this.
• Compiling the function to C-code, but syms, root(), and vpa() are not supported for code generation.

Is there any way to get this function or an equivalent to work in simulink?

Answer 1

[Wouter]

I have solved this issue by using coder.extrinsic, in essence I have the following function in simulink

function output  = symbolicFunctionSimulink(x0,x1,x2,x3,x4,x5)
coder.extrinsic('symbolicFunction');
output = 0; % initializing output
output = symbolicFunction(x0,x1,x2,x3,x4,x5);
end

and had to alter my symbolicFunction.m such that simulink recognized it to be numeric

function y  = symbolicFunction(x0,x1,x2,x3,x4,x5)
syms z
y = double(vpa(root(z^6 - z^4*(- 300*x2*x5 + 450*x2^2 + 450*x5^2) - z^3*(7200*x2*x1 + 4800*x2*x4 - 4800*x5*x1 - 7200*x5*x4) - z^2*(18000*x2*x0 - 18000*x2*x3 - 18000*x5*x0 + 18000*x5*x3 + 50400*x1*x4 + 28800*x1^2 + 28800*x4^2) - z*(144000*x1*x0 - 144000*x1*x3 + 144000*x4*x0 - 144000*x4*x3) + 360000*x0*x3 - 180000*x3^2 - 180000*x0^2, z, 1)));
end

This solved the problem for me.