Error in Matrix calculation

Hello I have been trying to debug this code, but am getting incorrect values in the final steps of the code. What this code does: 1) calculate the magnitude IVT (from x1 and y1) and then mask based on shape matrix 2) Sort IVT in descending order 3) Based on the sorting of IVT (index) sort x1 and y1 4) After x1 and y1 are sorted like that of IVT take the top N values at each element Note: the top N values are defined in the count matrix 5)To check do the same for sorted_ivt 6) To check calculate magnitude of ivtx1 and ivty1 and compare to totivt

count=[NaN 15 1; 2 NaN 2;NaN 4 3];

x1=randi(200,3,3,20);

y1=randi(200,3,3,20);

shape=randi(10,3,3,20);
shape(shape==5)=NaN; 

   %calcualte the magnitude 
  ivt1=sqrt(x1.^2+y1.^2);
  ivt1(isnan(shape))=0; %mask out 
  x1(isnan(shape))=0;
  y1(isnan(shape))=0;

%sort IVT in descending order 
[ivt_sorted,idx]=sort(ivt1,3,'descend');

%sort ivtx and ivty like that of ivt magnitude 

[m,n,o] = size(ivt1);
ivtx1 = x1((idx-1)*m*n + reshape(1:m*n,m,[]));

[m,n,o] = size(ivt1);
ivty1 = y1((idx-1)*m*n + reshape(1:m*n,m,[]));

check=sqrt(ivtx1.^2+ivty1.^2);
isequal(ivt_sorted,check)  %up to here they are the same!!!!!

%take the top N values based on count from ivtx, ivty, and ivt magnitude 

[m,n,k] = size(ivtx1);
count(isnan(count)) = 0;
out_ivt1= permute(reshape((1:k)'*ones(1,m*n) <= count(:)',[],m,n),[2,3,1]).*ivtx1;
out_ivt1(out_ivt1==0)=NaN;
Finalivtx=nanmean(out_ivt1(:,:,:),3);

[m,n,k] = size(ivty1);
count(isnan(count)) = 0;
out_ivt2= permute(reshape((1:k)'*ones(1,m*n) <= count(:)',[],m,n),[2,3,1]).*ivty1;
out_ivt2(out_ivt2==0)=NaN;
Finalivty=nanmean(out_ivt2(:,:,:),3);

[m,n,k] = size(ivt1);
count(isnan(count)) = 0;
check1= permute(reshape((1:k)'*ones(1,m*n) <= count(:)',[],m,n),[2,3,1]).*ivt1;
check1(check1==0)=NaN;
topivt=nanmean(check1(:,:,:),3);

test=sqrt(Topivtx.^2+Topivty.^2);  
isequal(test,topivt)  % THESE ARE NOT THE SAME!!!
%