Files
AMSS-NCKU/AMSS_NCKU_source/gaussj.C
CGH0S7 5956a952a0 Migrate build system from Intel oneAPI to AMD AOCC/AOCL toolchain
- Add TOOLCHAIN=aocc option with flang/clang++/mpicxx compilers
- Replace Intel flags (-xHost/-fma/-ipo/-qopenmp) with AOCC flags
  (-march=znver5/-ffast-math/-flto/-fopenmp) targeting EPYC 9755
- Replace Intel oneMKL with AMD AOCL (BLIS + libFLAME + amdlibm)
- Replace Intel TBBMALLOC with system jemalloc
- Change MKL-specific headers to standard CBLAS/LAPACKE
  (TwoPunctures.C, gaussj.C)
- Guard TBBMALLOC to Intel toolchain only

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-12 15:31:37 +08:00

107 lines
2.7 KiB
C

#ifdef newc
#include <iostream>
#include <iomanip>
#include <fstream>
#include <cstdlib>
#include <cstring>
#include <cmath>
using namespace std;
#else
#include <iostream.h>
#include <iomanip.h>
#include <fstream.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#endif
// LAPACKE interface (AOCL for AOCC, oneMKL for Intel)
#include <lapacke.h>
/* Linear equation solution using Intel oneMKL LAPACK.
a[0..n-1][0..n-1] is the input matrix. b[0..n-1] is input
containing the right-hand side vectors. On output a is
replaced by its matrix inverse, and b is replaced by the
corresponding set of solution vectors.
Mathematical equivalence:
Solves: A * x = b => x = A^(-1) * b
Original Gauss-Jordan and LAPACK dgesv/dgetri produce identical results
within numerical precision. */
int gaussj(double *a, double *b, int n)
{
// Allocate pivot array and workspace
lapack_int *ipiv = new lapack_int[n];
lapack_int info;
// Make a copy of matrix a for solving (dgesv modifies it to LU form)
double *a_copy = new double[n * n];
for (int i = 0; i < n * n; i++) {
a_copy[i] = a[i];
}
// Step 1: Solve linear system A*x = b using LU decomposition
// LAPACKE_dgesv uses column-major by default, but we use row-major
info = LAPACKE_dgesv(LAPACK_ROW_MAJOR, n, 1, a_copy, n, ipiv, b, 1);
if (info != 0) {
cout << "gaussj: Singular Matrix (dgesv info=" << info << ")" << endl;
delete[] ipiv;
delete[] a_copy;
return 1;
}
// Step 2: Compute matrix inverse A^(-1) using LU factorization
// First do LU factorization of original matrix a
info = LAPACKE_dgetrf(LAPACK_ROW_MAJOR, n, n, a, n, ipiv);
if (info != 0) {
cout << "gaussj: Singular Matrix (dgetrf info=" << info << ")" << endl;
delete[] ipiv;
delete[] a_copy;
return 1;
}
// Then compute inverse from LU factorization
info = LAPACKE_dgetri(LAPACK_ROW_MAJOR, n, a, n, ipiv);
if (info != 0) {
cout << "gaussj: Singular Matrix (dgetri info=" << info << ")" << endl;
delete[] ipiv;
delete[] a_copy;
return 1;
}
delete[] ipiv;
delete[] a_copy;
return 0;
}
// for check usage
/*
int main()
{
double *A,*b;
A=new double[9];
b=new double[3];
A[0]=0.5; A[1]=1.0/3; A[2]=1;
A[3]=1; A[4]=5.0/3; A[5]=3;
A[6]=2; A[7]=4.0/3; A[8]=5;
b[0]=1; b[1]=3; b[2]=2;
cout<<"initial data:"<<endl;
for(int i=0;i<3;i++) cout<<A[i*3]<<" "<<A[i*3+1]<<" "<<A[i*3+2]<<" "<<b[i]<<endl;
gaussj(A, b, 3);
cout<<"final data:"<<endl;
for(int i=0;i<3;i++) cout<<A[i*3]<<" "<<A[i*3+1]<<" "<<A[i*3+2]<<" "<<b[i]<<endl;
delete[] A; delete[] b;
}
*/