Create a LAPACK interface library

src/include/lapack_calls.h

+/*! \file lapack_calss.h
+ *
+ * \brief C++ interface to LAPACK calls.
+ *
+ */
+
+#ifndef INCLUDE_LAPACK_CALLS_H_
+#define INCLUDE_LAPACK_CALLS_H_
+
+/*! \brief Invert a complex matrix with double precision elements.
+ *
+ * Use LAPACKE64 to perform an in-place matrix inversion for a complex
+ * matrix with double precision elements.
+ *
+ * \param mat: Matrix of complex. The matrix to be inverted.
+ * \param n: `int` The number of rows and columns of the [n x n] matrix.
+ */
+void zinvert(std::complex<double> **mat, int n);
+
+#endif

src/libnptm/lapack_calls.cpp

+#include <complex>
+#include <cstdlib>
+#include "lapacke.h"
+
+#ifndef INCLUDE_LAPACK_CALLS_H_
+#define INCLUDE_LAPACK_CALLS_H_
+#include "../include/lapac_calls.h"
+#endif
+
+using namespace std;
+
+void zinvert(std::complex<double> **mat, int n){
+  __complex__ double *arr = new __complex__ double[n * n];
+  const __complex__ double uim = 1.0di;
+  for (int i = 0; i < n; i++) {
+    for (int j = 0; j < n; j++) {
+      int idx = i * n + j;
+      arr[idx] = mat[i][j].real() + uim * mat[i][j].imag();
+    }
+  }
+  
+  int* IPIV = new int[n];
+  
+  LAPACKE_zgetrf(LAPACK_ROW_MAJOR, N, N, arr, N, IPIV);
+  LAPACKE_zgetri(LAPACK_ROW_MAJOR, N, arr, N, IPIV);
+  for (int i = 0; i < n; i++) {
+    for (int j = 0; j < n; j++) {
+      int idx = i * n + j;
+      mat[i][j] = complex<double>(__real__ arr[idx], __imag__ arr[idx]);
+    }
+  }
+  delete [] IPIV;
+  delete [] arr;
+}