Error in HDL Coder- Fixed point conversion "MATLAB expression 'r' is not of the correct class: expected 'double', found 'sym'."

Question

radhia bouazizi 2020-8-23

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https://ww2.mathworks.cn/matlabcentral/answers/583469-error-in-hdl-coder-fixed-point-conversion-matlab-expression-r-is-not-of-the-correct-class-expe

回答： Kiran Kintali 2020-8-25

Hi,I tried basic examples of MATLAB to HDL conversions like levenberg . Then I tried running this code.

Code

function xc=LevenbergMarquardt(r,x,x0,epsilon,n,lambda)
%Levenberg Marquardt Method for nonlinear least squares
%Input: r is the nonlinear fitting function model
%       x is the coefficients in the fitting function that needs to be
%       determined
%       x0 is the initial values
%       epsilon is the tolerance
%       lambda is the regularization term coefficient
%Output: xc is the determined coefficients
r=double(0);
x0=x0(:);
x=x(:);
coder.extrinsic('jacobian');
coder.extrinsic('subs');
J=jacobian(r,x);
a=1;
A0=double(0);
A0=double(subs(J,x,x0));
r0=double(subs(r,x,x0));
v=double(0);
v=-(A0'*A0+lambda*eye(length(x)))\(A0'*r0);
w=double(0);
w=A0'*r0;
x0=x0+v;
while(norm(w)>epsilon)
    A0=double(subs(J,x,x0));
    r0=double(subs(r,x,x0));  
    v=-(A0'*A0+lambda*eye(length(x)))\(A0'*r0);
    x0=x0+v;
    a=a+1;
    if a>n break;
    end
end
xc=x0;
end

Please help me ,i write a test bench. I am getting error when I try to validate the fixed point type conversion . It fails giving errors in simulation output of test "

MATLAB expression 'r' is not of the correct class: expected 'double', found 'sym'.".

My test bench is

clear all;
clc;close all;
syms c1 c2 c3 t y
Y=c1*exp(-c2*(t-c3)^2)-y;
x1=[-1 0 1 3 6];
x1=x1';
z1=[1 5 10 8 1];
z1=z1';
x2=[1 2 4 5 6 8 9 11];
x2=x2';
z2=[1 3 7 12 13 5 2 1];
z2=z2';
c=[c1;c2;c3];
epsilon=0.5e-8;
n=30;
display('********************************');
display('For exercise (a)');
display('********************************');
r1=subs(Y,{t,y},{x1,z1});
c0=[10;0;2];
lambda=1;
c_root1=LevenbergMarquardt(r1,c,c0,epsilon,n,lambda);
display('The coefficients found by using LevenbergMarquardt method are:');
display(['c=[c1;c2;c3]=' mat2str(c_root1)]);
f1=c_root1(1).*exp(-c_root1(2).*(x1-c_root1(3)).^2);
aError=f1-z1;
aRMSE=norm(aError,2);
display(['RMSE=' num2str(aRMSE)]);
figure(1);
plot(x1,z1,'o','MarkerFaceColor','g','MarkerSize',8);
hold on;
a=-2:0.1:8;
g1=c_root1(1).*exp(-c_root1(2).*(a-c_root1(3)).^2);
plot(a,g1,'b');
title('Levenberg-Marquardt fitting');
display('********************************');
display('For exercise (b)');
display('********************************');
r2=subs(Y,{t,y},{x2,z2});
c0=[10;0;2];
lambda=0.5;
c_root2=LevenbergMarquardt(r2,c,c0,epsilon,n,lambda);
display('The coefficients found by using LevenbergMarquardt method are:');
display(['c=[c1;c2;c3]=' mat2str(c_root2)]);
f2=c_root2(1).*exp(-c_root2(2).*(x2-c_root2(3)).^2);
bError=f2-z2;
bRMSE=norm(bError,2);
display(['RMSE=' num2str(bRMSE)]);
figure(2);
plot(x2,z2,'o','MarkerFaceColor','g','MarkerSize',8);
hold on;
a=0:0.01:12;
g2=c_root2(1).*exp(-c_root2(2).*(a-c_root2(3)).^2);
plot(a,g2,'b');
title('Levenberg-Marquardt fitting');

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Answer 1

Steven Lord 2020-8-24

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/583469-error-in-hdl-coder-fixed-point-conversion-matlab-expression-r-is-not-of-the-correct-class-expe#answer_484040

None of the functions from Symbolic Math Toolbox are on the list of functions supported for HDL code generation. I haven't used HDL Coder before but I'm virtually certain you will not be able to generate HDL code from code that uses Symbolic Math Toolbox functionality.

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Steven Lord 2020-8-24

I don't work with VHDL at all so I don't have any recommendations. Please contact Technical Support using the telephone icon in the upper-right corner of this page to ask how (or if) you can implement the Levenberg-Marquardt algorithm in VHDL.

radhia bouazizi 2020-8-24