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function C = gb_prod (op, type, G, option)
%GB_PROD C = prod (G), using the given operator and type
% Implements C = prod (G) and C = all (G).
% SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2022, All Rights Reserved.
% SPDX-License-Identifier: Apache-2.0
[m, n] = gbsize (G) ;
if (nargin == 3)
% C = prod (G)
if (m == 1 || n == 1)
option = 'all' ;
else
option = 1 ;
end
end
switch (option)
case { 'all' }
% C = prod (G, 'all'), reducing all entries to a scalar
if (m*n == gbnvals (G))
C = gbreduce (op, G) ;
else
C = gbnew (0, type) ;
end
case { 1 }
% C = prod (G,1) reduces each column to a scalar,
% giving a 1-by-n row vector.
% M = find (column degree of G == m)
M = gbselect (gbdegree (G, 'col'), '==', int64 (m)) ;
Cin = gbnew (n, 1, type) ;
% C<M> = op (G')
desc.in0 = 'transpose' ;
C = gbtrans (gbvreduce (Cin, M, op, G, desc)) ;
case { 2 }
% C = prod (G,2) reduces each row to a scalar,
% giving an m-by-1 column vector.
% M = find (row degree of G == n)
M = gbselect (gbdegree (G, 'row'), '==', int64 (n)) ;
% C<M> = op (G)
Cin = gbnew (m, 1, type) ;
C = gbvreduce (Cin, M, op, G) ;
otherwise
error ('GrB:error', 'unknown option') ;
end
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