diff --git a/src/lib/sgd.cpp b/src/lib/sgd.cpp
index a0f04bd..2764c71 100644
--- a/src/lib/sgd.cpp
+++ b/src/lib/sgd.cpp
@@ -25,34 +25,25 @@
  */
 enum sgd_return_e
 {
-	SGD_SUCCESS = 0,
-	SGD_CONVERGENCE = 1,
-	SGD_STOP, //2
-	SGD_UNKNOWN_ERROR = -1024,
-	// The variable size is negative
-	SGD_INVILAD_VARIABLE_SIZE, //-1023
-	// The maximal iteration times is negative.
-	SGD_INVILAD_MAX_ITERATIONS, //-1022
-	// The epsilon is negative.
-	SGD_INVILAD_EPSILON, //-1021
-	// Iteration reached max limit
-	SGD_REACHED_MAX_ITERATIONS,
-	// Invalid value for mu
-	SGD_INVALID_MU,
-	// Invalid value for alpha
-	SGD_INVALID_ALPHA,
-	// Invalid value for beta
-	SGD_INVALID_BETA,
-	// Invalid value for sigma
-	SGD_INVALID_SIGMA,
-	// Nan value
-	SGD_NAN_VALUE,
+	SGD_SUCCESS = 0, ///< The optimization terminated successfully.
+	SGD_CONVERGENCE = 1, ///< The optimization reached convergence.
+	SGD_STOP, ///< The process stopped by the monitoring function.
+	SGD_UNKNOWN_ERROR = -1024, ///< Unknown error.
+	SGD_INVALID_VARIABLE_SIZE, ///< The variable size is negative
+	SGD_INVALID_MAX_ITERATIONS, ///< The maximal iteration times is negative.
+	SGD_INVALID_EPSILON, ///< The epsilon is negative.
+	SGD_REACHED_MAX_ITERATIONS, ///< Iteration reached max limit.
+	SGD_INVALID_MU, ///< Invalid value for mu.
+	SGD_INVALID_ALPHA, ///< Invalid value for alpha.
+	SGD_INVALID_BETA, ///< Invalid value for beta.
+	SGD_INVALID_SIGMA, ///< Invalid value for sigma.
+	SGD_NAN_VALUE, ///< Nan value.
 };
 
 /**
  * Default parameter for the SGD methods.
  */
-static const sgd_para defparam = {100, 1e-6, 0.01, 0.001, 0.9, 0.999, 1e-8};
+static const sgd_para defparam = {300, 1e-6, 0.01, 0.001, 0.9, 0.999, 1e-8};
 
 sgd_float *sgd_malloc(const int n_size)
 {
@@ -85,13 +76,13 @@ const char* sgd_error_str(int er_index)
 			return "The iteration stopped by the progress evaluation function.";
 		case SGD_UNKNOWN_ERROR:
 			return "Unknown error.";
-		case SGD_INVILAD_VARIABLE_SIZE:
+		case SGD_INVALID_VARIABLE_SIZE:
 			return "Invalid array size.";
-		case SGD_INVILAD_MAX_ITERATIONS:
+		case SGD_INVALID_MAX_ITERATIONS:
 			return "Invalid maximal iteration times.";
 		case SGD_REACHED_MAX_ITERATIONS:
 			return "The maximal iteration is reached.";
-		case SGD_INVILAD_EPSILON:
+		case SGD_INVALID_EPSILON:
 			return "Invalid value for epsilon.";
 		case SGD_INVALID_BETA:
 			return "Invalid value for beta.";
@@ -190,9 +181,9 @@ int momentum(sgd_evaulate_ptr Evafp, sgd_progress_ptr Profp, sgd_float *fx, sgd_
 	sgd_para para = (param != nullptr) ? (*param) : defparam;
 
 	//check parameters
-	if (n_size <= 0) return SGD_INVILAD_VARIABLE_SIZE;
-	if (para.iteration <= 0) return SGD_INVILAD_MAX_ITERATIONS;
-	if (para.epsilon < 0) return SGD_INVILAD_EPSILON;
+	if (n_size <= 0) return SGD_INVALID_VARIABLE_SIZE;
+	if (para.iteration <= 0) return SGD_INVALID_MAX_ITERATIONS;
+	if (para.epsilon < 0) return SGD_INVALID_EPSILON;
 	if (para.mu < 0 || para.mu >= 1.0) return SGD_INVALID_MU;
 
 	sgd_float *mk = sgd_malloc(n_size);
@@ -238,9 +229,9 @@ int nag(sgd_evaulate_ptr Evafp, sgd_progress_ptr Profp, sgd_float *fx, sgd_float
 	sgd_para para = (param != nullptr) ? (*param) : defparam;
 
 	//check parameters
-	if (n_size <= 0) return SGD_INVILAD_VARIABLE_SIZE;
-	if (para.iteration <= 0) return SGD_INVILAD_MAX_ITERATIONS;
-	if (para.epsilon < 0) return SGD_INVILAD_EPSILON;
+	if (n_size <= 0) return SGD_INVALID_VARIABLE_SIZE;
+	if (para.iteration <= 0) return SGD_INVALID_MAX_ITERATIONS;
+	if (para.epsilon < 0) return SGD_INVALID_EPSILON;
 	if (para.mu < 0 || para.mu >= 1.0) return SGD_INVALID_MU;
 
 	sgd_float *mk = sgd_malloc(n_size);
@@ -293,9 +284,9 @@ int adagrad(sgd_evaulate_ptr Evafp, sgd_progress_ptr Profp, sgd_float *fx, sgd_f
 	sgd_para para = (param != nullptr) ? (*param) : defparam;
 
 	//check parameters
-	if (n_size <= 0) return SGD_INVILAD_VARIABLE_SIZE;
-	if (para.iteration <= 0) return SGD_INVILAD_MAX_ITERATIONS;
-	if (para.epsilon < 0.0) return SGD_INVILAD_EPSILON;
+	if (n_size <= 0) return SGD_INVALID_VARIABLE_SIZE;
+	if (para.iteration <= 0) return SGD_INVALID_MAX_ITERATIONS;
+	if (para.epsilon < 0.0) return SGD_INVALID_EPSILON;
 	if (para.sigma < 0.0) return SGD_INVALID_SIGMA;
 
 	sgd_float *mk = sgd_malloc(n_size);
@@ -341,9 +332,9 @@ int rmsprop(sgd_evaulate_ptr Evafp, sgd_progress_ptr Profp, sgd_float *fx, sgd_f
 	sgd_para para = (param != nullptr) ? (*param) : defparam;
 
 	//check parameters
-	if (n_size <= 0) return SGD_INVILAD_VARIABLE_SIZE;
-	if (para.iteration <= 0) return SGD_INVILAD_MAX_ITERATIONS;
-	if (para.epsilon < 0.0) return SGD_INVILAD_EPSILON;
+	if (n_size <= 0) return SGD_INVALID_VARIABLE_SIZE;
+	if (para.iteration <= 0) return SGD_INVALID_MAX_ITERATIONS;
+	if (para.epsilon < 0.0) return SGD_INVALID_EPSILON;
 	if (para.sigma < 0.0) return SGD_INVALID_SIGMA;
 
 	sgd_float *vk = sgd_malloc(n_size);
@@ -389,9 +380,9 @@ int adam(sgd_evaulate_ptr Evafp, sgd_progress_ptr Profp, sgd_float *fx, sgd_floa
 	sgd_para para = (param != nullptr) ? (*param) : defparam;
 
 	//check parameters
-	if (n_size <= 0) return SGD_INVILAD_VARIABLE_SIZE;
-	if (para.iteration <= 0) return SGD_INVILAD_MAX_ITERATIONS;
-	if (para.epsilon < 0) return SGD_INVILAD_EPSILON;
+	if (n_size <= 0) return SGD_INVALID_VARIABLE_SIZE;
+	if (para.iteration <= 0) return SGD_INVALID_MAX_ITERATIONS;
+	if (para.epsilon < 0) return SGD_INVALID_EPSILON;
 	if (para.alpha < 0) return SGD_INVALID_ALPHA;
 	if (para.beta_1 < 0.0 || para.beta_1 >= 1.0) return SGD_INVALID_BETA;
 	if (para.beta_2 < 0.0 || para.beta_2 >= 1.0) return SGD_INVALID_BETA;
@@ -451,9 +442,9 @@ int nadam(sgd_evaulate_ptr Evafp, sgd_progress_ptr Profp, sgd_float *fx, sgd_flo
 	sgd_para para = (param != nullptr) ? (*param) : defparam;
 
 	//check parameters
-	if (n_size <= 0) return SGD_INVILAD_VARIABLE_SIZE;
-	if (para.iteration <= 0) return SGD_INVILAD_MAX_ITERATIONS;
-	if (para.epsilon < 0) return SGD_INVILAD_EPSILON;
+	if (n_size <= 0) return SGD_INVALID_VARIABLE_SIZE;
+	if (para.iteration <= 0) return SGD_INVALID_MAX_ITERATIONS;
+	if (para.epsilon < 0) return SGD_INVALID_EPSILON;
 	if (para.alpha < 0) return SGD_INVALID_ALPHA;
 	if (para.beta_1 < 0.0 || para.beta_1 >= 1.0) return SGD_INVALID_BETA;
 	if (para.beta_2 < 0.0 || para.beta_2 >= 1.0) return SGD_INVALID_BETA;
@@ -523,9 +514,9 @@ int adamax(sgd_evaulate_ptr Evafp, sgd_progress_ptr Profp, sgd_float *fx, sgd_fl
 	if (param == nullptr) para.alpha = 0.002;
 
 	//check parameters
-	if (n_size <= 0) return SGD_INVILAD_VARIABLE_SIZE;
-	if (para.iteration <= 0) return SGD_INVILAD_MAX_ITERATIONS;
-	if (para.epsilon < 0) return SGD_INVILAD_EPSILON;
+	if (n_size <= 0) return SGD_INVALID_VARIABLE_SIZE;
+	if (para.iteration <= 0) return SGD_INVALID_MAX_ITERATIONS;
+	if (para.epsilon < 0) return SGD_INVALID_EPSILON;
 	if (para.alpha < 0) return SGD_INVALID_ALPHA;
 	if (para.beta_1 < 0.0 || para.beta_1 >= 1.0) return SGD_INVALID_BETA;
 	if (para.beta_2 < 0.0 || para.beta_2 >= 1.0) return SGD_INVALID_BETA;
@@ -581,9 +572,9 @@ int adabelief(sgd_evaulate_ptr Evafp, sgd_progress_ptr Profp, sgd_float *fx, sgd
 	sgd_para para = (param != nullptr) ? (*param) : defparam;
 
 	//check parameters
-	if (n_size <= 0) return SGD_INVILAD_VARIABLE_SIZE;
-	if (para.iteration <= 0) return SGD_INVILAD_MAX_ITERATIONS;
-	if (para.epsilon < 0) return SGD_INVILAD_EPSILON;
+	if (n_size <= 0) return SGD_INVALID_VARIABLE_SIZE;
+	if (para.iteration <= 0) return SGD_INVALID_MAX_ITERATIONS;
+	if (para.epsilon < 0) return SGD_INVALID_EPSILON;
 	if (para.alpha < 0) return SGD_INVALID_ALPHA;
 	if (para.beta_1 < 0.0 || para.beta_1 >= 1.0) return SGD_INVALID_BETA;
 	if (para.beta_2 < 0.0 || para.beta_2 >= 1.0) return SGD_INVALID_BETA;
diff --git a/src/lib/sgd.h b/src/lib/sgd.h
index a3b64a9..6dd998b 100644
--- a/src/lib/sgd.h
+++ b/src/lib/sgd.h
@@ -86,12 +86,12 @@ typedef enum
 } sgd_solver_enum;
 
 /**
- * @brief    Parameters of the Adam method.
+ * @brief    Parameters of the SGD methods.
  */
 typedef struct
 {
 	/**
-	 * Iteration times for the entire observation set. The default is 100.
+	 * Iteration times for the entire observation set. The default is 300.
 	 */
 	int iteration;