quad2d: Reached the maximum number of function evaluations

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I'm trying to find the error in the following code. I want to iterate:
for iter = 1:10
% uallA = Int_GLA.*(-Int_GC - Int_GB) + Int_GA;
uallA = Int_GLA.*(-uallC - uallB) + Int_GA;
uallB = Int_GLB.*(-uallC - uallB) + Int_GB;
uallC = Int_GLC.*(-uallC - uallB) + Int_GC;
end
However, I receive the following error:
Warning: Reached the maximum number of function evaluations (2000). The result fails the global error test.
This is my code:
clc; clear all; close all;
x = linspace(-10, 10, 51);
t = linspace(0.1, 5, 51);
nx = length(x);
nt = length(t);
Wx = x(2) - x(1);
Wt = t(2) - t(1);
f = @(x) exp(-x.^2);
%%A right
for mx = 1:nx
for mt = 1:nt
GA = @(xi) 1./sqrt(4*pi*(t(mt))).*exp(-(x(mx) - xi).^2./(4*(t(mt)))).*exp(-xi.^2);
funGA = quad(GA, x(1), x(end));
Int_GA(mx, mt) = funGA;
end
end
figure(1)
surf(t,x, Int_GA)
xlabel('t')
ylabel('x')
zlabel('u')
%%B right
for mx = 1:nx
for mt = 1:nt
GB = @(xi) 1./sqrt(4*pi*(t(mt))).*exp(-(x(mx) - xi).^2./(4*(t(mt))))...
.*(-(x(mx) - xi)/(2*t(mt))).*exp(-xi.^2);
funGB = quad(GB, x(1), x(end));
Int_GB(mx, mt) = funGB;
end
end
figure(2)
surf(t,x, Int_GB)
xlabel('t')
ylabel('x')
zlabel('u')
%%C right
for mx = 1:nx
for mt = 1:nt
GC = @(xi) 1./sqrt(4*pi*(t(mt))).*exp(-(x(mx) - xi).^2./(4*(t(mt))))...
.*((x(mx)-xi).^2/(4*t(mt).^2) - 1./(2*t(mt))).*exp(-xi.^2);
funGC = quad(GC, x(1), x(end));
Int_GC(mx, mt) = funGC;
end
end
figure(3)
surf(t,x, Int_GC)
xlabel('t')
ylabel('x')
zlabel('u')
%%A left
for mt1 = 1:nt
for mx1 = 1:nx
GLA = @(xi, ta) 1./sqrt(4*pi*(t(mt1)-ta)).*exp(-(x(mx1) - xi).^2 ...
./(4*(t(mt1)-ta)));
funGLA = quad2d(GLA, x(1), x(end), t(1), t(mt1), 'AbsTol',1e-4, 'FailurePlot',true);
Int_GLA(mx1, mt1) = funGLA;
end
end
figure(4)
surf(t,x, Int_GLA)
xlabel('t')
ylabel('x')
zlabel('u')
%%B left
for mt2 = 1:nt
for mx2 = 1:nx
GLB = @(xi, ta) -(x(mx2) - xi)./(2*(t(mt2) - ta))./sqrt(4*pi*(t(mt2)-ta))...
.*exp(-(x(mx2) - xi).^2 ./(4*(t(mt2)-ta)));
funGLB = quad2d(GLB, x(1), x(end), t(1), t(mt2), 'AbsTol',1e-4, 'FailurePlot',true);
Int_GLB(mx2, mt2) = funGLB;
end
end
%%C left
for mt3 = 1:nt
for mx3 = 1:nx
GLC = @(xi, ta) 1./(4*(t(mt3)-ta).^2).*((x(mx3) - xi).^2 - ...
2*(t(mt3)-ta))./sqrt(4*pi*(t(mt3)-ta)).*exp(-(x(mx3) - xi).^2 ...
./(4*(t(mt3)-ta)));
funGLC = quad2d(GLC, x(1), x(end), t(1), t(mt3), 'AbsTol',1e-4, 'FailurePlot',true);
Int_GLC(mx3, mt3) = funGLC;
end
end
uallB = zeros(nx, nt);
uallC = zeros(nx, nt);
for iter = 1:10
% uallA = Int_GLA.*(-Int_GC - Int_GB) + Int_GA;
uallA = Int_GLA.*(-uallC - uallB) + Int_GA;
uallB = Int_GLB.*(-uallC - uallB) + Int_GB;
uallC = Int_GLC.*(-uallC - uallB) + Int_GC;
end
% uallA1 = Int_GA;
% uallB1 = Int_GB;
% uallC1 = Int_GC;
% uallA = Int_GLA.*(-uallC1 - uallB1) + Int_GA;
figure(5)
surf(t,x, uallA)
xlabel('t')
ylabel('x')
zlabel('u')

Accepted Answer

Walter Roberson
Walter Roberson on 16 Jan 2013
The problem is not occurring in the "for iter" loop that you point out: it is occurring in the quad2d() call.
You should add a MaxFunEvals parameter to your quad2d() call.
Also you should be examining your failure plot.
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