Error : Inner matrix dimensions must agree When computing the three dimensional integral.

Error : Inner matrix dimensions must agree When computing the three dimensional integral.

The code is as follows:

        m1 = 20;
        v1 = 60;
        m2 = 20;
        v2 = 60;
        m3 = 20;
        v3 = 60;
        cov = [ 60,0,0;
                0,60,0;
                0,0,60]
        cov1=inv(cov)
      
        f = @(z,y,x) exp( ([(x-m1),(y-m2),(z-m3)]*(cov1)*[(x-m1);(y-m2);(z-m3)])./(-2) )
        P1 = triplequad(f,0,1000,0,1000,0,1000);

I am eager to getting the solution.... Anyone has any comments? I would appreciate !!!!!