function gbtest28
%GBTEST28 test GrB.build

% SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2020, All Rights
% Reserved. http://suitesparse.com.  See GraphBLAS/Doc/License.txt.

fprintf ('\ngbtest28: testing GrB.build and compare with A=sparse(i,j,x)\n') ;
nthreads = GrB.threads ;
fprintf ('using %d threads in GraphBLAS\n', nthreads) ;

rng ('default') ;
m = 10 ;
n = 5 ;
A = sprand (m, n, 0.5) ;

[i, j, x] = find (A) ;

C = GrB.build (i, j, x, m, n) ;

assert (gbtest_eq (C, A)) ;

fprintf ('\nGenerating large test matrix; please wait ...\n') ;
n = 1000 ;
nz = 7000 ;
density = nz / n^2 ;
tic
A = sprand (n, n, density) ;
B = sprand (n, n, density) ;
A = kron (A,B) ;
clear B
t = toc ;
n = size (A, 1) ;
fprintf ('%12.4f sec : A n-by-n, with n: %g nnz: %g\n', t, n, nnz (A)) ;

[i, j, x] = find (A) ;
[m, n] = size (A) ;

i0 = uint64 (i) - 1 ;
j0 = uint64 (j) - 1 ;

fprintf ('\nwith [I J] already sorted on input:\n') ;

tic
A1 = sparse (i, j, x, m, n) ;
t = toc ;
fprintf ('%12.4f sec : A = sparse (i, j, x, m, n) ;\n', t) ;

tic
A3 = GrB.build (i, j, x, m, n) ;
t = toc ;
fprintf ('%12.4f sec : A = GrB.build (...), same inputs as MATLAB\n', t) ;

d.kind = 'sparse' ;

tic
A4 = GrB.build (i, j, x, m, n, d) ;
t = toc ;
fprintf ('%12.4f sec : A = GrB.build (...), same inputs/outputs as MATLAB\n',t);

desc0.base = 'zero-based' ;
tic
A2 = GrB.build (i0, j0, x, m, n, desc0) ;
t = toc ;
fprintf ('%12.4f sec : A = GrB.build (i0, j0, ...), with i0 and j0 uint64\n',t);

assert (gbtest_eq (A1, A2)) ;
assert (gbtest_eq (A1, A3)) ;
assert (gbtest_eq (A1, A4)) ;

fprintf ('\nwith [I J] jumbled so that a sort is required:\n') ;

i = i (end:-1:1) ;
j = j (end:-1:1) ;
i (1:10) = i (randperm (10)) ;
i0 = uint64 (i) - 1 ;
j0 = uint64 (j) - 1 ;

tic
A1 = sparse (i, j, x, m, n) ;
t = toc ;
fprintf ('%12.4f sec : A = sparse (i, j, x, m, n) ;\n', t) ;

tic
A3 = GrB.build (i, j, x, m, n) ;
t = toc ;
fprintf ('%12.4f sec : A = GrB.build (...), same inputs as MATLAB\n', t) ;

tic
A4 = GrB.build (i, j, x, m, n, d) ;
t = toc ;
fprintf ('%12.4f sec : A = GrB.build (...), same inputs/outputs as MATLAB\n',t);

tic
A2 = GrB.build (i0, j0, x, m, n, desc0) ;
t = toc ;
fprintf ('%12.4f sec : A = GrB.build (i0,j0,...), with i0 and j0 uint64\n', t) ;

assert (gbtest_eq (A1, A2)) ;
assert (gbtest_eq (A1, A3)) ;
assert (gbtest_eq (A1, A4)) ;

fprintf ('\ngbtest28: all tests passed\n') ;

