From 6e388f3d990e2dc9848e94b0942cea5700faae8a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Max=20L=C3=BCbke?= <mluebke@uni-potsdam.de>
Date: Tue, 5 Sep 2023 16:38:54 +0200
Subject: [PATCH] write input of thomas algortithm to file

---
 src/BTCSv2.cpp     | 27 +++++++++++++++++++++++++++
 src/CMakeLists.txt |  6 ++++++
 2 files changed, 33 insertions(+)

diff --git a/src/BTCSv2.cpp b/src/BTCSv2.cpp
index 49e4d1c..705b152 100644
--- a/src/BTCSv2.cpp
+++ b/src/BTCSv2.cpp
@@ -11,6 +11,11 @@
 #include <tug/Boundary.hpp>
 #include <omp.h>
 
+#ifdef WRITE_THOMAS_CSV
+#include<fstream>
+#include<string>
+#endif
+
 #define NUM_THREADS_BTCS 10
 
 using namespace Eigen;
@@ -295,6 +300,28 @@ static VectorXd ThomasAlgorithm(SparseMatrix<double> &A, VectorXd &b) {
     a_diag[n - 1] = A.coeff(n - 1, n - 2);
     b_diag[n - 1] = A.coeff(n - 1, n - 1);
 
+    // HACK: write CSV to file
+#ifdef WRITE_THOMAS_CSV
+    #include<fstream>
+    #include<string>
+    static std::uint32_t file_index = 0;
+    std::string file_name = "Thomas_" + std::to_string(file_index++) + ".csv";
+
+    std::ofstream out_file;
+
+    out_file.open(file_name, std::ofstream::trunc | std::ofstream::out);
+
+    // print header
+    out_file << "Aa, Ab, Ac, b\n";
+
+    // iterate through all elements
+    for (std::size_t i = 0; i < n; i++) {
+        out_file << a_diag[i] << ", " << b_diag[i] << ", " << c_diag[i] << ", " << b[i] << "\n";
+    }
+
+    out_file.close();
+#endif
+
     // start solving - c_diag and x_vec are overwritten
     n--;
     c_diag[0] /= b_diag[0];
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index b7aceb2..3cc79d4 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,5 +1,11 @@
 add_library(tug Boundary.cpp Grid.cpp Simulation.cpp FTCS.cpp BTCSv2.cpp)
 
+option(TUG_WRITE_CSV "Write CSV during Thomas algorithm with consecutive numbers for each call" OFF)
+
+IF(TUG_WRITE_CSV)
+  target_compile_definitions(tug PRIVATE WRITE_THOMAS_CSV)
+endif()
+
 target_link_libraries(tug Eigen3::Eigen)
 
 if(TUG_USE_OPENMP AND OpenMP_CXX_FOUND)