diff --git a/src/diffusion.cpp b/src/diffusion.cpp
index 726fdf2..5b398a2 100644
--- a/src/diffusion.cpp
+++ b/src/diffusion.cpp
@@ -46,7 +46,8 @@ void BTCS1D(int x, std::vector<double> &c, std::vector<double> &alpha,
 
   A_line++;
   tripletList.push_back(T(A_line, size-1, 1));
-  b[A_line] = bc[1];
+  // b[A_line] = bc[1];
+  b[A_line] = c[c.size()-1];
 
   // std::cout << b << std::endl;
 
diff --git a/src/diffusion.hpp b/src/diffusion.hpp
index 6645f8c..9d80e45 100644
--- a/src/diffusion.hpp
+++ b/src/diffusion.hpp
@@ -6,6 +6,9 @@
 
 typedef Eigen::Triplet<double> T;
 
+extern void BTCS1D(int x, std::vector<double> &c, std::vector<double> &alpha,
+                   double timestep, std::vector<double> &bc);
+
 extern void BTCS2D(int x, int y, std::vector<double> &c,
                    std::vector<double> &alpha, double timestep);
 #endif // DIFFUSION_H_
diff --git a/src/main.cpp b/src/main.cpp
index be66bcc..3613d17 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -7,16 +7,20 @@ using namespace std;
 
 int main(int argc, char *argv[]) {
 
-  int x = 4;
-  int y = 4;
+  int x = 20;
 
-  std::vector<double> alpha(x * y, 1 * pow(10, -9));
-  std::vector<double> input(x * y, 1 * std::pow(10,-6));
-  input[x + 1] = 5 * std::pow(10, -6);
+  std::vector<double> alpha(x, 1 * pow(10, -1));
+  std::vector<double> input(x, 1 * std::pow(10, -6));
+  std::vector<double> bc;
+
+  bc.push_back(5. * std::pow(10, -6));
+  bc.push_back(1. * std::pow(10, -6));
   // input[x + 2] = 5.5556554 * std::pow(10, -6);
   // input[x + 3] = 5.234564213 * std::pow(10, -6);
 
-  BTCS2D(x, y, input, alpha, 1.);
+  for (int i = 0; i < 100; i++) {
+    BTCS1D(x, input, alpha, 1., bc);
+  }
 
   return 0;
 }