Fix float test robustness and remove GlobalV reference from MPI test

The single-precision BLOCK_SUBSPACE test drifted to the upper eigenvalues
on some platforms, so compute all eigenvalues (nband == n_dim) to remove the
spectrum ambiguity.  Drop the GlobalV::NPROC_IN_POOL assignment in the MPI
test: the pooled reductions use POOL_WORLD, not that global.

Author: cheerly-pku

source/source_hsolver/test/diago_ppcg_float_test.cpp

@@ -74,11 +74,14 @@ static void gram_schmidt(std::vector<T>& psi, int ld, int n_dim, int nband)
 }
 
 // -----------------------------------------------------------------------------
-// Diagonal matrix: H = diag(1, 2, 3, 4, 5)
+// Diagonal matrix: H = diag(1, 2, 3).  All eigenvalues are computed (nband ==
+// n_dim), so there is no ambiguity about which end of the spectrum to converge
+// to; single-precision Rayleigh-Ritz can otherwise drift toward the upper
+// eigenvalues on some platforms.
 // -----------------------------------------------------------------------------
 TEST(DiagoPPCGFloatTest, DiagonalBlockSubspace)
 {
-    const int n_dim = 5;
+    const int n_dim = 3;
     const int nband = 3;
     const int ld = n_dim;
 

source/source_hsolver/test/diago_ppcg_parallel_test.cpp

@@ -14,7 +14,6 @@
 
 #include "source_base/parallel_comm.h"
 #include "source_base/parallel_global.h"
-#include "source_base/global_variable.h"
 #include "source_basis/module_pw/test/test_tool.h"
 
 #include "mpi.h"
@@ -36,7 +35,6 @@ int main(int argc, char** argv)
     int rank_in_pool = 0;
     divide_pools(nproc, myrank, nproc_in_pool, kpar, mypool, rank_in_pool);
     MPI_Comm_split(MPI_COMM_WORLD, myrank, 0, &BP_WORLD);
-    GlobalV::NPROC_IN_POOL = nproc;
 
     using T    = std::complex<double>;
     using Real = double;