first commit

2026-01-18 20:37:50 +08:00
commit fff9f18287
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--- a/src/ComputeResidual.cpp
+++ b/src/ComputeResidual.cpp
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+
+//@HEADER
+// ***************************************************
+//
+// HPCG: High Performance Conjugate Gradient Benchmark
+//
+// Contact:
+// Michael A. Heroux ( maherou@sandia.gov)
+// Jack Dongarra     (dongarra@eecs.utk.edu)
+// Piotr Luszczek    (luszczek@eecs.utk.edu)
+//
+// ***************************************************
+//@HEADER
+
+/*!
+ @file ComputeResidual.cpp
+
+ HPCG routine
+ */
+#ifndef HPCG_NO_MPI
+#include <mpi.h>
+#endif
+#ifndef HPCG_NO_OPENMP
+#include <omp.h>
+#endif
+
+#include "Vector.hpp"
+
+#ifdef HPCG_DETAILED_DEBUG
+#include "hpcg.hpp"
+#include <fstream>
+#endif
+
+#include "ComputeResidual.hpp"
+#include <cmath> // needed for fabs
+#ifdef HPCG_DETAILED_DEBUG
+#include <iostream>
+#endif
+
+/*!
+  Routine to compute the inf-norm difference between two vectors where:
+
+  @param[in]  n        number of vector elements (local to this processor)
+  @param[in]  v1, v2   input vectors
+  @param[out] residual pointer to scalar value; on exit, will contain result: inf-norm difference
+
+  @return Returns zero on success and a non-zero value otherwise.
+*/
+int ComputeResidual(const local_int_t n, const Vector& v1, const Vector& v2, double& residual)
+{
+
+    double* v1v = v1.values;
+    double* v2v = v2.values;
+    double local_residual = 0.0;
+
+#ifndef HPCG_NO_OPENMP
+#pragma omp parallel shared(local_residual, v1v, v2v)
+    {
+        double threadlocal_residual = 0.0;
+#pragma omp for
+        for (local_int_t i = 0; i < n; i++)
+        {
+            double diff = std::fabs(v1v[i] - v2v[i]);
+            if (diff > threadlocal_residual)
+                threadlocal_residual = diff;
+        }
+#pragma omp critical
+        {
+            if (threadlocal_residual > local_residual)
+                local_residual = threadlocal_residual;
+        }
+    }
+#else // No threading
+    for (local_int_t i = 0; i < n; i++)
+    {
+        double diff = std::fabs(v1v[i] - v2v[i]);
+        if (diff > local_residual)
+            local_residual = diff;
+#ifdef HPCG_DETAILED_DEBUG
+        HPCG_fout << " Computed, exact, diff = " << v1v[i] << " " << v2v[i] << " " << diff << std::endl;
+#endif
+    }
+#endif
+
+#ifndef HPCG_NO_MPI
+    // Use MPI's reduce function to collect all partial sums
+    double global_residual = 0;
+    MPI_Allreduce(&local_residual, &global_residual, 1, MPI_DOUBLE, MPI_MAX, MPI_COMM_WORLD);
+    residual = global_residual;
+#else
+    residual = local_residual;
+#endif
+
+    return 0;
+}