r - Vectorization in Stan

Question

I need a multiplication of arrays in Stan. But the multiplication uses too many for sentences and, probably, it causes the codes need a lot of time. So, If possible, I want to use vectorization in Stan file. But I am not sure how to vectorize it. For example, I consider the following codes in which the multiplication of arrays b[1,i,j,k]=a[i,j,k]*x[i,j,k] are used. I want to vectorize this. My idea is something like b[1,,,]=a*x.

In the following, I showed an example of Stan code.

 data{  real x[222,333,444]; }
                
 parameter{   real a[111,222,333,444];  }

 transformed parameter{
        real b[111,222,333,444];
        
        for(i in 1:222){
        for(j in 1:333){
        for(k in 1:444){
         b[1,i,j,k]=a[i,j,k]*x[i,j,k];
        }}}
        
        
        
       // b[1,,,]=a*x; // As far as I am concerned, this vectorization dose not work. 
        
        
            }

question from:https://stackoverflow.com/questions/65860527/vectorization-in-stan

Answer 1

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