Error using sqpInterface Objective function is undefined at initial point.

while using nmpc example of the inverted pendulum.I am getting this error. I just change model to double pendulum model in pendulumCT.m file. what should I do?

Error using sqpInterface
Objective function is undefined at initial point. Fmincon cannot continue.

Error in fmincon (line 808)
    [X,FVAL,EXITFLAG,OUTPUT,LAMBDA,GRAD,HESSIAN] = sqpInterface(funfcn,X,full(A),full(B),full(Aeq),full(Beq), ...

Error in nmpc (line 52)
    uopt = fmincon(COSTFUN,uopt,[],[],[],[],LB,UB,CONSFUN,options);

Answer 1

[Jacob Bean]

First try evaluating your cost function with your initial guess and see if you can actually get an output. I believe that fmincon expects the output of the cost function to be a real scalar value. Double check that you're not outputting a complex quantity.

[Scott Pham]

Hi!

I am having the same issue. My cost function is complex variable scalar function, relative error Erel which should be close to zero. I supplied gradient of cost function qV with respest to position, I haven't supplr constrains on material properties yet. I basically already solved inverse problem and minimized Erel, I need to find a configuration that satisfies the constrains for both position of configuration and material properties of each scatterrer. In the past I used fmincon for real function but this time I am solving inverse problem, and cost function is complex values. Can fmincon deal with it? I have some outputs and error message below.

Thanks in advance,

Feruza. I was not able to inlcude my info. My email is: [e-mail]

Erel =

2.4496e-12 - 4.3748e-15i

qV =

1.0e-11 *

0.0000 + 0.0000i

0.0000 + 0.0000i

0.0000 + 0.0000i

0.0000 + 0.0000i

0.0000 + 0.0000i

0.0000 + 0.0000i

0.0000 + 0.0000i

0.0000 + 0.0000i

-0.1168 + 0.0034i

0.0430 - 0.0004i

Error using sqpInterface

Objective function is undefined at initial point. Fmincon cannot continue.

Error in fmincon (line 833)

[X,FVAL,EXITFLAG,OUTPUT,LAMBDA,GRAD,HESSIAN] =

sqpInterface(funfcn,X,full(A),full(B),full(Aeq),full(Beq), ...

Error in main_InverseScatteringPattern_fmincon (line 176)

[x,fval,exitflag,output,grad] =

fmincon(objective,x0,A,b,Aeq,beq,lb,ub,nonlincon,options);

Answer 2

[kamilya MIMOUNI]

error using sqpInterface

Objective function is undefined at initial point. Fmincon cannot continue.

Error in fmincon (line 823)

[X,FVAL,EXITFLAG,OUTPUT,LAMBDA,GRAD,HESSIAN] = sqpInterface(funfcn,X,full(A),full(B),full(Aeq),full(Beq), ...

Error in Test3 (line 89)

Control_optimal = fmincon(problem)

i have this problem in matlab

please help me

Answer 3

[kamilya MIMOUNI]

function Test3

clear;close all; clc

% For starting

fprintf ( 1, '\n' );

fprintf ( 1, 'Test1:\n' );

fprintf ( 1, ' MATLAB version:\n' );

fprintf ( 1, ' A program to demonstrate the finite element method.\n' );

% Geometry data

rin = 0.2; rex = 1;

gd1 = [1;1.6;0;rex];

gd2 = [1;1.6;0;rin];

gd = [gd1,gd2];

ns = (char('Cext','Cint'))';

sf = 'Cext - Cint';

[dl, bt] = decsg(gd, sf, ns);

model = createpde;

geometryFromEdges(model,dl);

pdegplot(model,'EdgeLabels','on','FaceLabels','on')

msh = generateMesh(model,'Hmax',0.05,'GeometricOrder','linear','Jiggle','on');

[p,e,t] = meshToPet(msh);

% [p,e,t] = refinemesh(dl,p,e,t);

% return

coordinates = p';

elements3 = t(1:3,:)';

Ne = findNodes(msh,'region','Edge',(1:4));

Ni = findNodes(msh,'region','Edge',(5:8));

neumann = [Ni(:),[Ni(2:end)';Ni(1)]];

dirichlet = [Ne(:),[Ne(2:end)';Ne(1)]];

BoundNodes = unique(dirichlet);

% Export Initial Data

load flux_initial.mat flux_initial resultss Nee

uintrp = interpolateSolution(resultss,p(1,:),p(2,:));

uintrp(Ne) = 1;

[uintrpx,uintrpy] = pdegrad(p,t,uintrp); % au centre des triangles

uintrpxn = pdeprtni(p,t,uintrpx); % au noeuds

uintrpyn = pdeprtni(p,t,uintrpy); % au noeuds

Nx = @(z)2*z(1,:);

Ny = @(z)2*z(2,:);

z = p(:,Ne);

nx = Nx(z); nx = nx(:);

ny = Ny(z); ny = ny(:);

epsilon = 3/10;

h_flux = 1./(sqrt(nx.^2+ny.^2).*sqrt(z(1,:)'.^2+z(2,:)'.^2).*uintrpxn(Ne).*nx+uintrpyn(Ne).*ny);

% Direct problem

RHS_step = zeros(size(elements3,1));

a_x = zeros(size(elements3,1));

c_x = zeros(size(elements3,1));

Control = zeros(size(neumann,1),1);

for j=1:size(elements3,1)

xc = sum(coordinates(elements3(j,:),:))/3;

RHS_step(j) = 0;

c_x(j) = 1./(1+epsilon*xc(1));

a_x(j) = 0;

end

psi_d = ones(size(BoundNodes,1),1); % fct g sur Gamma_ex

for j=1:size(neumann,1)

x_m = sum(coordinates(neumann(j,:),:))/2; % vecteur ligne: coordonnées du milieu du segment

Control(j) = 1; % le controle v sur Gamma_in

end

[psi,psi_flux] = Direct_Problem(elements3,neumann,coordinates,c_x,a_x,RHS_step,Control,psi_d,BoundNodes,p,t, ...

epsilon,nx,ny,Ne,z);

% Cost function

regu = 1/1000;

Integrand = psi_flux - h_flux;

Cost_J = Cost_Function(Control,Integrand,coordinates,Ne,Ni,rex,rin,regu);

if(Cost_J==0)

disp('Your intial guess v = 1 is exactely your solution')

disp('There is no need for optimization')

end

disp('fmincon start')

% options = optimoptions('fmincon','Display','iter','Algorithm','sqp','PlotFcns', ...

% {@optimplotfval,@optimplotfirstorderopt},'TolFun',4.0e-4);

% options = optimoptions(@fmincon,'GradObj','on','Display','iter','TolFun',1.0e-4, ...

% 'PlotFcns',{@optimplotfval,@optimplotfirstorderopt});

lb = 4.0e-2*ones(size(Control,1),1);

ub = 5*ones(size(Control,1),1);

options = optimoptions('fmincon','Display','iter','Algorithm','sqp');

problem.options = options;

problem.solver = 'fmincon';

problem.objective = @(u_epsilon)Moncef_Cost_Function(u_epsilon,elements3,neumann,coordinates,c_x,a_x,RHS_step, ...

BoundNodes,p,t,epsilon,nx,ny,Ne,Ni,z,rex,rin,regu,h_flux);

problem.x0 = Control;

problem.nonlcon = [];

Control_optimal = fmincon(problem)

Control_optimal = fmincon(@(u_epsilon)Moncef_Cost_Function(u_epsilon,elements3,neumann,coordinates,c_x,a_x,RHS_step, ...

BoundNodes,p,t,epsilon,nx,ny,Ne,Ni,z,rex,rin,regu,h_flux), ...

Control,[],[],[],[],lb,ub,[],options);

% Retour au probleme direct final

[psi,psi_flux] = Direct_Problem(elements3,neumann,coordinates,c_x,a_x,RHS_step,Control_optimal,psi_d,BoundNodes,p,t, ...

epsilon,nx,ny,Ne,z);

% ep = 0.2;

% Nb = findNodes(msh,'box',[-1-ep -1],[-0.5 0.5]);

%[i,c] = pdesdp(p,e,t,sdl);

figure(10)

pdemesh(model_initial)

hold on

plot(msh.Nodes(1,Nee),msh.Nodes(2,Nee),'or','MarkerFaceColor','g')

psi_full = full(psi);

psi_max = max(psi_full(Nee));

indice2 = find(psi_full<=psi_max+0.07 & psi_full>=psi_max-0.07);

k = convhull(p(1,indice2),p(2,indice2));

figure(12)

pdemesh(model)

hold on

plot(p(1,k),p(2,k),'r-')

figure(11)

pdegplot(model)

hold on

plot(msh.Nodes(1,indice2),msh.Nodes(2,indice2),'.r','MarkerFaceColor','r')

Answer 4

[kamilya MIMOUNI]

function probleme_initial

close all; clear all; clc

R0 = 3/2;

a1 = 0.5;

N = 40;

angles = 0:2*pi/N:2*pi; angles = angles(1:end-1);

absi = (R0*sqrt(1+2*a1*cos(angles)/R0)-R0)./a1; absi = absi(:);

ord = a1*R0*sin(angles)./a1; ord = ord(:);

% Geometry data

poly = [absi,ord];

gd1 = [2;length(poly);poly(:,1);poly(:,2)];

abs = linspace(-1,1,N); abs = abs(end:-1:1);

abs = [abs,abs(end-1:-1:2)];

poly1 = [absi(:),ord(:)];

%======================================

ep = 0.1;

abs2 = [-1;-1;-1-ep;-1-ep];

ord2 = [-0.5;0.5;0.5;-0.5];

poly2 = [abs2,ord2];

gd2 = zeros(size(gd1));

gd2(1) = 2;

gd2(2) = length(poly2);

gd2(3:length(poly2(:,1))+2) = poly2(:,1);

gd2(length(poly2(:,1))+3:length(poly2(:,1))+2+length(poly2(:,2))) = poly2(:,2);

% gd2 = [2;length(poly2);poly2(:,1);poly2(:,2)];

%=============================================

gd3 = zeros(size(gd1)); gd3(1) = 1; gd3(4) = 2;

gd = [gd1,gd3];

ns = (char('D','Cext'))';

sf = 'Cext - D';

[dl, bt] = decsg(gd, sf, ns);

model= createpde;

geometryFromEdges(model,dl);

pdegplot(model,'EdgeLabels','on','FaceLabels','on')

% return

applyBoundaryCondition(model,'dirichlet','Edge',(41:44),'h',1,'r',1);

% applyBoundaryCondition(model,'dirichlet','Edge',(1:198),'h',1,'r',1);

% applyBoundaryCondition(model,'dirichlet','Edge',(1:40),'h',1,'r',20);

% applyBoundaryCondition(model,'dirichlet','Edge',(1:40),'h',1,'r',40);

applyBoundaryCondition(model,'dirichlet','Edge',(1:40),'h',1,'r',50);

axis equal

msh = generateMesh(model,'Hmax',0.05,'GeometricOrder','linear','Jiggle','on');

[p,e,t] = meshToPet(msh);

z1 = p(:);

C=1./sqrt(z1(1,:)'.^2+z1(2,:)'.^2);

specifyCoefficients(model, 'm', 0, 'd', 0, 'c', C, 'a', 0, 'f', 0);

resultss = solvepde(model);

u= resultss.NodalSolution;

figure(3)

pdeplot(p, e, t, 'xydata', u, 'contour', 'on', 'mesh', 'off');

axis equal

ux = resultss.XGradients;

uy = resultss.YGradients;

Nee = findNodes(msh,'region','Edge',(41:44));

psi_fr = psi(Nee);

Nx = @(z) 2*z(1,:);

Ny = @(z) 2*z(2,:);

z = p(:,Nee);

nx = Nx(z); nx = nx(:);

ny = Ny(z); ny = ny(:);

Flux11 = (ux(Nee).*nx+uy(Nee).*ny)./sqrt(nx.^2+ny.^2);

Flux1 = Flux11./sqrt(z(1,:)'.^2+z(2,:)'.^2);

flux_initial = [z',Flux1];

save flux_initial.mat flux_initial resultss Nee