Calculation of integrals and summation with an error "The following error occurred converting from gpuArray to double: Conversion to double from gpuArray is not possible"

Hello. I try to reduce the time for the performance of the following code using Parallel Computing Toolbox

    function z=test_GPU
    tic

    tt=-0.000689609;t=0.242731; muu=0.365908;

    f_f=gpuArray.linspace(0,100,101); f_b=gpuArray.linspace(-3000,3000,6001);
    [m,NN]=meshgrid(f_f,f_b);

        y1= @(N,q,k) t*q./k.*log((-k.^2+2*k.*q-q.^2+muu+1i*(2*pi*N.*t-(2*m(1,:)+1)*pi*t))./(-k.^2-2*k.*q-...
            q.^2+muu+1i*(2*pi*N.*t-(2*m(1,:)+1)*pi*t)))./(tt*pi+integral(@(a)a.*tanh((a.^2-muu)./(2*t)).*log((2*a.^2+2*a.*q+...
            q.^2-2*muu-1i*2*pi*N*t)./(2*a.^2-2*a.*q+q.^2-2*muu-1i*2*pi*N*t))./q-2,0,10000,'AbsTol',1e-5,'RelTol',1e-3,'ArrayValued',true));

          R1=@(q,k) integral(@(N)y1(N,q,k),3000,10^6,'AbsTol',1e-5,'RelTol',1e-3,'ArrayValued',true);
          R11=@(q,k) integral(@(N)y1(N,q,k),-10^6,-3000,'AbsTol',1e-5,'RelTol',1e-3,'ArrayValued',true);

        y2=@(q,k) t*q./k.*log((-k.^2+2*k.*q-q.^2+muu+1i*(2*pi*NN(:,1).*t-(2*m(1,:)+1)*pi*t))./(-k.^2-2*k.*q-...
            q.^2+muu+1i*(2*pi*NN(:,1).*t-(2*m(1,:)+1)*pi*t)))./(tt*pi+integral(@(a)a.*tanh((a.^2-muu)./(2*t)).*log((2*a.^2+2*a.*q+...
            q.^2-2*muu-1i*2*pi*NN(:,1).*t)./(2*a.^2-2*a.*q+q.^2-2*muu-1i*2*pi*NN(:,1).*t))./q-2,0,10000,'AbsTol',1e-5,'RelTol',1e-3,'ArrayValued',true));

        R2=@(q,k) sum(y2(q,k));
        S=@(q,k) R1(q,k)+R11(q,k)+R2(q,k)-4*sqrt(2)/pi*(1/1000)/(pi^(3/2)*sqrt(t))*q.^2; 

    Sigma=@(k) integral(@(q)S(q,k),0.001,7,'AbsTol',1e-5,'RelTol',1e-3,'ArrayValued',true);

    A=Sigma(1);
    A=gather(A);
    plot(m(1,:),real(A),m(1,:),imag(A))
    grid on

    toc
    end

Without GPU on my computer I have around 1 minute calculation time. But with GPU unfortunately I got an error ""The following error occurred converting from gpuArray to double: Conversion to double from gpuArray is not possible". What is the problem here? Thank you in a advance for any comments.

[Matt J]

What is the full error message?

[Yuriy Yerin]

The following error occurred converting from gpuArray to double:
Conversion to double from gpuArray is not possible.

Error in integralCalc/iterateArrayValued (line 184)
                qsubs(:,1) = qsubsk(:);

Error in integralCalc/vadapt (line 130)
            [q,errbnd] = iterateArrayValued(u,tinterval,pathlen);

Error in integralCalc (line 75)
        [q,errbnd] = vadapt(@AtoBInvTransform,interval);

Error in integral (line 88)
Q = integralCalc(fun,a,b,opstruct);

Error in test_GPU>@(q,k)integral(@(N)y1(N,q,k),3000,10^6,'AbsTol',1e-5,'RelTol',1e-3,'ArrayValued',true)
(line 24)
      R1=@(q,k) integral(@(N)y1(N,q,k),3000,10^6,'AbsTol',1e-5,'RelTol',1e-3,'ArrayValued',true);

Error in test_GPU>@(q,k)R1(q,k)+R11(q,k)+R2(q,k)-4*sqrt(2)/pi*(1/1000)/(pi^(3/2)*sqrt(t))*q.^2 (line 32)
    S=@(q,k) R1(q,k)+R11(q,k)+R2(q,k)-4*sqrt(2)/pi*(1/1000)/(pi^(3/2)*sqrt(t))*q.^2;

Error in test_GPU>@(q)S(q,k) (line 40)
Sigma=@(k) integral(@(q)S(q,k),0.001,7,'AbsTol',1e-5,'RelTol',1e-3,'ArrayValued',true);

Error in integralCalc/iterateArrayValued (line 156)
                fxj = FUN(t(1)).*w(1);

Error in integralCalc/vadapt (line 130)
            [q,errbnd] = iterateArrayValued(u,tinterval,pathlen);

Error in integralCalc (line 75)
        [q,errbnd] = vadapt(@AtoBInvTransform,interval);

Error in integral (line 88)
Q = integralCalc(fun,a,b,opstruct);

Error in test_GPU>@(k)integral(@(q)S(q,k),0.001,7,'AbsTol',1e-5,'RelTol',1e-3,'ArrayValued',true) (line
40)
Sigma=@(k) integral(@(q)S(q,k),0.001,7,'AbsTol',1e-5,'RelTol',1e-3,'ArrayValued',true);

Error in test_GPU (line 42)
A=Sigma(1);

Answer 1

[Joss Knight]

On the face of it this code is not very advisable to run on the GPU, since I don't think it is well vectorized. Still, for a pointer, this error comes when you try to assign a gpuArray into elements of a non-CPU array.

A(indices) = gpuArray(b);

So you could try checking that everything you're passing to integral is a gpuArray.

However, it's just as likely that the assignment is something integral is doing internally because it doesn't natively support gpuArray data.

[Yuriy Yerin]

Thank you for the response. It was just attempt to improve the performance of my code. So that's why I tried to find the answer. Thanks again