Error using fmincon, the function cannot continue
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Hi, everyone.
I'm trying to optimize a function with 8 optimization variables. I set up initial point and costraints but appears the following error:
"Error using optim.problemdef.OptimizationProblem/solve
Objective function is undefined at initial point. Fmincon cannot continue.
Error in curvatura_V7 (line 75)
[sol,fval,exitflag,output] = solve(prob,x0);"
the code is as follow:
aymax = 5;
V = 70;
deltay = 60;
deltax = 3;
intorno = sqrt(deltax^2+deltay^2);
dmin = 3;
type objfun
rof1 = optimvar('rof1');
rof2 = optimvar('rof2');
rof3 = optimvar('rof3');
rof4 = optimvar('rof4');
sf1 = optimvar('sf1');
sf2 = optimvar('sf2');
sf3 = optimvar('sf3');
sf4 = optimvar('sf4');
obj = fcn2optimexpr(@objfun,rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4);
prob = optimproblem('Objective',obj);
constr1 = (-aymax / (V/3.6)^2) <= rof1;
prob.Constraints.curvatura1 = constr1;
constr2 = (aymax / (V/3.6)^2) >= rof1;
prob.Constraints.curvatura1 = constr2;
constr3 = (-aymax / (V/3.6)^2) <= rof2;
prob.Constraints.curvatura2 = constr3;
constr4 = (aymax / (V/3.6)^2) >= rof2;
prob.Constraints.curvatura2 = constr4;
constr5 = (-aymax / (V/3.6)^2) <= rof3;
prob.Constraints.curvatura3 = constr5;
constr6 = (aymax / (V/3.6)^2) >= rof3;
prob.Constraints.curvatura3 = constr6;
constr7 = (-aymax / (V/3.6)^2) <= rof4;
prob.Constraints.curvatura4 = constr7;
constr8 = (aymax / (V/3.6)^2) >= rof4;
prob.Constraints.curvatura4 = constr8;
constr9 = sf1 >= 0 ;
prob.Constraints.ascissa1 = constr9;
constr10 = sf1 <= sf2;
prob.Constraints.ascissa1 = constr10;
constr11 = sf2 >= sf1;
prob.Constraints.ascissa2 = constr11;
constr12 = sf2 <= sf3;
prob.Constraints.ascissa2 = constr12;
constr13 = sf3 >= sf1+sf2;
prob.Constraints.ascissa3 = constr13;
constr14 = sf3 <= sf4;
prob.Constraints.ascissa3 = constr14;
constr15 = sf4 >= sf1+sf2+sf3;
prob.Constraints.ascissa4 = constr15;
constr16 = sf4 <= 2*intorno;
prob.Constraints.ascissa4 = constr16;
show(prob)
x0.rof1 = 0;
x0.rof2 = 0;
x0.rof3 = 0;
x0.rof4 = 0;
x0.sf1 = 0;
x0.sf2 = 0;
x0.sf3 = 0;
x0.sf4 = 0;
[sol,fval,exitflag,output] = solve(prob,x0);
Accepted Answer
aymax = 5;
V = 70;
deltay = 60;
deltax = 3;
intorno = sqrt(deltax^2+deltay^2);
dmin = 3;
rof1 = optimvar('rof1');
rof2 = optimvar('rof2');
rof3 = optimvar('rof3');
rof4 = optimvar('rof4');
sf1 = optimvar('sf1');
sf2 = optimvar('sf2');
sf3 = optimvar('sf3');
sf4 = optimvar('sf4');
obj = fcn2optimexpr(@objfun,rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4);
prob = optimproblem('Objective',obj);
constr1 = (-aymax / (V/3.6)^2) <= rof1;
prob.Constraints.curvatura1 = constr1;
constr2 = (aymax / (V/3.6)^2) >= rof1;
prob.Constraints.curvatura1 = constr2;
constr3 = (-aymax / (V/3.6)^2) <= rof2;
prob.Constraints.curvatura2 = constr3;
constr4 = (aymax / (V/3.6)^2) >= rof2;
prob.Constraints.curvatura2 = constr4;
constr5 = (-aymax / (V/3.6)^2) <= rof3;
prob.Constraints.curvatura3 = constr5;
constr6 = (aymax / (V/3.6)^2) >= rof3;
prob.Constraints.curvatura3 = constr6;
constr7 = (-aymax / (V/3.6)^2) <= rof4;
prob.Constraints.curvatura4 = constr7;
constr8 = (aymax / (V/3.6)^2) >= rof4;
prob.Constraints.curvatura4 = constr8;
constr9 = sf1 >= 0 ;
prob.Constraints.ascissa1 = constr9;
constr10 = sf1 <= sf2;
prob.Constraints.ascissa1 = constr10;
constr11 = sf2 >= sf1;
prob.Constraints.ascissa2 = constr11;
constr12 = sf2 <= sf3;
prob.Constraints.ascissa2 = constr12;
constr13 = sf3 >= sf1+sf2;
prob.Constraints.ascissa3 = constr13;
constr14 = sf3 <= sf4;
prob.Constraints.ascissa3 = constr14;
constr15 = sf4 >= sf1+sf2+sf3;
prob.Constraints.ascissa4 = constr15;
constr16 = sf4 <= 2*intorno;
prob.Constraints.ascissa4 = constr16;
show(prob)
x0.rof1 = 0;
x0.rof2 = 0;
x0.rof3 = 0;
x0.rof4 = 0;
x0.sf1 = 0;
x0.sf2 = 0;
x0.sf3 = 0;
x0.sf4 = 0;
%[sol,fval,exitflag,output] = solve(prob,x0);
result = objfun(x0.rof1, x0.rof2, x0.rof3, x0.rof4, x0.sf1, x0.sf2, x0.sf3, x0.sf4)
function erroredistanza = objfun(rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4)
deltay = 60;
deltax = 3;
tau0 = 90;
tau0 = deg2rad(tau0);
dmin = 3;
roi1=0;
si1=0;
PSI1 = @(roi1,rof1,si1,sf1,s) tau0 + ((rof1*si1-roi1*sf1)/(si1-sf1))*s + ((roi1-rof1)/(si1-sf1))*(s.^2)/2;
PSI2 = @(rof1,rof2,sf1,sf2,s) ((rof2*sf1-rof1*sf2)/(sf1-sf2))*s + ((rof1-rof2)/(sf1-sf2))*(s.^2)/2;
PSI3 = @(rof2,rof3,sf2,sf3,s) ((rof3*sf2-rof2*sf3)/(sf2-sf3))*s + ((rof2-rof3)/(sf2-sf3))*(s.^2)/2;
PSI4 = @(rof3,rof4,sf3,sf4,s) ((rof4*sf3-rof3*sf4)/(sf3-sf4))*s + ((rof3-rof4)/(sf3-sf4))*(s.^2)/2;
funx1 = @(roi1,rof1,si1,sf1,s) integral(@(s) cos(PSI1(roi1,rof1,si1,sf1,s)),0,sf1);
funx2 = @(rof1,rof2,sf1,sf2,s) integral(@(s) cos(PSI2(rof1,rof2,sf1,sf2,s)),sf1,sf2);
funx3 = @(rof2,rof3,sf2,sf3,s) integral(@(s) cos(PSI3(rof2,rof3,sf2,sf3,s)),sf2,sf3);
funx4 = @(rof3,rof4,sf3,sf4,s) integral(@(s) cos(PSI4(rof3,rof4,sf3,sf4,s)),sf3,sf4);
funy1 = @(roi1,rof1,si1,sf1,s) integral(@(s) sin(PSI1(roi1,rof1,si1,sf1,s)),0,sf1);
funy2 = @(rof1,rof2,sf1,sf2,s) integral(@(s) sin(PSI2(rof1,rof2,sf1,sf2,s)),sf1,sf2);
funy3 = @(rof2,rof3,sf2,sf3,s) integral(@(s) sin(PSI3(rof2,rof3,sf2,sf3,s)),sf2,sf3);
funy4 = @(rof3,rof4,sf3,sf4,s) integral(@(s) sin(PSI4(rof3,rof4,sf3,sf4,s)),sf3,sf4);
funx = @(rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4) funx1(roi1,rof1,si1,sf1) + funx2(rof1,rof2,sf1,sf2) + funx3(rof2,rof3,sf2,sf3) + funx4(rof3,rof4,sf3,sf4);
funy = @(rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4) funy1(roi1,rof1,si1,sf1) + funy2(rof1,rof2,sf1,sf2) + funy3(rof2,rof3,sf2,sf3) + funy4(rof3,rof4,sf3,sf4);
fun2x =@(rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4) funx(rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4) - deltax;
fun2y =@(rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4) funy(rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4) - deltay;
fun3x =@(rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4) fun2x(rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4).^2;
fun3y =@(rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4) fun2y(rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4).^2;
d =@(rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4) sqrt(fun3x(rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4) + fun3y(rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4));
erroredistanza = d(rof1,rof2,rof3,rof4,sf1,sf2,sf3,sf4) - dmin;
end
... Look at the code. You divide by (si1-sf1) and (sf1-sf2) and (sf2-sf3) and (sf3-sf4) . si1 is 0, and sf1 to sf4 are passed in. Your initial values for all of the variables is 0, so you are dividing by (0-0) in multiple places.
If you divide by something in your objective, it is your responsibility to ensure that your constraints exclude the possibility that you are going to be dividing by 0, and that your initial point is not going to trigger a division by 0.
1 Comment
Andrea Mazzetto
on 21 Jun 2021
More Answers (1)
Tarunbir Gambhir
on 18 Jun 2021
1 vote
The error message says the objective function is not defined at initial point. This means objfun(xo) returns a 'NaN' or errors out (where "objfun" is objective function and "xo" is the initial point). It could be that the initial point does not satisfy all the provided constraints for the objective function. Since you did not provide the 'objfun', I would not be able to help any further.
Anyway, to avoid this error you can simply try choosing a better initial point.
1 Comment
Andrea Mazzetto
on 19 Jun 2021
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