Why does version R2020b gives errors when running functions such as fmincon, when version R2019a runs properly.

This is the code I'm running:

clear;clc
syms x y z
f=8*x.^2+y.^3;
c=5-x-y;
L=f-z*c;
dL_dx=matlabFunction(diff(L,x),'Vars',[x,y,z]);
dL_dy=matlabFunction(diff(L,y),'Vars',[x,y,z]);
dL_dz=matlabFunction(diff(L,z),'Vars',[x,y,z]);
d2L_dx2=matlabFunction(diff(dL_dx,x),'Vars',[x,y,z]);
d2L_dxy=matlabFunction(diff(dL_dx,y),'Vars',[x,y,z]);
d2L_dxz=matlabFunction(diff(dL_dx,z),'Vars',[x,y,z]);
d2L_dyx=matlabFunction(diff(dL_dy,x),'Vars',[x,y,z]);
d2L_dy2=matlabFunction(diff(dL_dy,y),'Vars',[x,y,z]);
d2L_dyz=matlabFunction(diff(dL_dy,z),'Vars',[x,y,z]);
d2L_dzx=matlabFunction(diff(dL_dz,x),'Vars',[x,y,z]);
d2L_dzy=matlabFunction(diff(dL_dz,y),'Vars',[x,y,z]);
d2L_dz2=matlabFunction(diff(dL_dz,z),'Vars',[x,y,z]);
max_iterations=100;
x_search=zeros(1,max_iterations);
y_search=zeros(1,max_iterations);
z_search=zeros(1,max_iterations);
x_search(1)=2;
y_search(1)=2;
z_search(1)=0;
for n=1:max_iterations
    h11=d2L_dx2(x_search(n),y_search(n),z_search(n));
    h12=d2L_dxy(x_search(n),y_search(n),z_search(n));
    h13=d2L_dxz(x_search(n),y_search(n),z_search(n));
    h21=d2L_dyx(x_search(n),y_search(n),z_search(n));
    h22=d2L_dy2(x_search(n),y_search(n),z_search(n));
    h23=d2L_dyz(x_search(n),y_search(n),z_search(n));
    h31=d2L_dzx(x_search(n),y_search(n),z_search(n));
    h32=d2L_dzy(x_search(n),y_search(n),z_search(n));
    h33=d2L_dz2(x_search(n),y_search(n),z_search(n));
    H=[h11,h12,h13;...
       h21,h22,h23;...
       h31,h32,h33];
    grad=[dL_dx(x_search(n),y_search(n),z_search(n));...
          dL_dy(x_search(n),y_search(n),z_search(n));...
          dL_dz(x_search(n),y_search(n),z_search(n))];
          
          temp=[x_search(n);y_search(n);z_search(n)]-H^-1*grad;
          x_search(n+1)=temp(1);
          y_search(n+1)=temp(2);
          z_search(n+1)=temp(3);         
end
clear L
L=@(x) 8*x(1)^2+x(2)^3;
x0=[x_search(1);y_search(1)];
A=[];
b=[];
Aeq=[1 1];
beq=5;
xmin=fmincon(L,x0,A,b,Aeq,beq);
[x1,x2]=meshgrid(-4:0.01:4);
z=8*x1.^2+x2.^3;
figure;hold on
mesh(x1,x2,z)
plot(-4:0.01:4,5-(-4:0.01:4),'r')
xlabel('x1');ylabel('x2');zlabel('f')
figure;hold on
contour(x1,x2,z,20)
plot(-4:0.01:4,5-(-4:0.01:4),'r')
plot(x_search,y_search,'g')
xlabel('x1');ylabel('x2');zlabel('f')
grid

When I run it at school on version R2019a everything works. When I run it at home on version R2020b I get the following error message:

Unrecognized function or variable 'getIpOptions'.

Error in fmincon (line 846)

options = getIpOptions(options,sizes.nVar,mEq,flags.constr,defaultopt,10,0.01);

Error in example_2 (line 66)

xmin=fmincon(L,x0,A,b,Aeq,beq);

Answer 1

[Bjorn Gustavsson]

Have you installed the optimization toolbox in your 2020b install? If not that is where that function resides.

Check the existence of functions with the which command:

which getIpOptions -all

HTH

[Vitas Diktanas]

Thank you. That was it. Just had to go to Add-Ons to install. Everything is working properly now.

[Bjorn Gustavsson]

Good!

(The general advice (perhaps?) is to install everything you have the license for. If collaborating with someone that has access to a smaller number of toolboxes it is sometimes tricky to not include handy functions from some "too specialised" toolbox...)