diff --git a/src/poly/coeff/private/polyCoeff.cpp b/src/poly/coeff/private/polyCoeff.cpp
index 870e817..aa56bbd 100644
--- a/src/poly/coeff/private/polyCoeff.cpp
+++ b/src/poly/coeff/private/polyCoeff.cpp
@@ -4,20 +4,15 @@
 #include "polyCoeff.h"
 
 namespace polycoeff{
-  double xi_coeff_func(const mfem::Vector &x)
+  double nonlinearSourceCoeff(const mfem::Vector &x)
   {
-    return std::pow(x(0), 2);
+    // double r = x.Norml2();
+    return 1.0;
   }
 
-  void vec_xi_coeff_func(const mfem::Vector &x, mfem::Vector &v)
+  void diffusionCoeff(const mfem::Vector &x, mfem::Vector &v)
   {
-    v.SetSize(1);
-    v[0] = -std::pow(x(0), 2);
-  }
-
-  double theta_initial_guess(const mfem::Vector &x, double root)
-  {
-    double xi = x[0];
-    return 1 - std::pow(xi / root, 2);
+    v.SetSize(3);
+    for (int i = 0; i < 3; i++) { v(i) = -1; }
   }
 }
\ No newline at end of file
diff --git a/src/poly/coeff/public/polyCoeff.h b/src/poly/coeff/public/polyCoeff.h
index 4a1e81d..663ddaf 100644
--- a/src/poly/coeff/public/polyCoeff.h
+++ b/src/poly/coeff/public/polyCoeff.h
@@ -12,7 +12,7 @@ namespace polycoeff
    * @param x Input vector.
    * @return double The computed xi coefficient.
    */
-    double xi_coeff_func(const mfem::Vector &x);
+    double nonlinearSourceCoeff(const mfem::Vector &x);
 
   /**
    * @brief Computes the vector xi coefficient function.
@@ -20,16 +20,7 @@ namespace polycoeff
    * @param x Input vector.
    * @param v Output vector to store the computed xi coefficient.
    */
-    void vec_xi_coeff_func(const mfem::Vector &x, mfem::Vector &v);
-
-  /**
-   * @brief Computes the initial guess for theta.
-   * 
-   * @param x Input vector.
-   * @param root Root value used in the computation.
-   * @return double The initial guess for theta.
-   */
-    double theta_initial_guess(const mfem::Vector &x, double root);
+    void diffusionCoeff(const mfem::Vector &x, mfem::Vector &v);
 } // namespace polyCoeff
 
 #endif // POLYCOEFF_H
\ No newline at end of file