Re: [Boost-users] proto for array expressions

Subject: Re: [Boost-users] proto for array expressions
From: James Sutherland (James.Sutherland_at_[hidden])
Date: 2008-12-18 17:50:33

On Dec 18, 2008, at 3:46 PM, Eric Niebler wrote:

> Daniel Oberhoff wrote:
>> Now with proto I was wondering how hard it would be to build an et  
>> engine for array math. Basically I am interested in general tensor  
>> notation, and the resulting expressions should be iteratable  
>> efficiently. think (advanced example):
>> a_ij = b_i * (c_j - sum(d_ijk, k = [i-1,1])
>
> I don't understand your notation. What are a_ij et. al.?
>
Presumably Einstein notation:
   a_i  = vector
   a_ij  = 2D matrix
   a_ijk = 3D array
so that
   b_i c_j
is the outer product of two vectors, producing a matrix...

James