From: Yu-Chin <guestwalk@gmail.com>
Date: Tue, 21 Oct 2014 19:32:51 +0000 (+0800)
Subject: In get_decfun_coef and get_decfun_bias, a zero value is returned in all invalid
X-Git-Tag: v195~3
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=f9c13dff5ad1b32e4a67eaed77c13365a86c68d7;p=liblinear

In get_decfun_coef and get_decfun_bias, a zero value is returned in all invalid
cases. We decide not to return NaN because we are not sure if it can be
properly assigned in all platforms. (For example, ``double nan = 0.0/0.0;''
won't compile in Visual Studio.)
---

diff --git a/README b/README
index 2560287..9ea3381 100644
--- a/README
+++ b/README
@@ -453,15 +453,18 @@ Library Usage
 
     This function gives the coefficient for the feature with feature index =
     feat_idx and the class with label index = label_idx. Note that feat_idx
-    starts from 1, while label_idx starts from 0. If label_idx is not in the
-    valid range (0 to nr_class-1), then a NaN will be returned; and if feat_idx
-    is not in the valid range (1 to nr_feature), then a zero value will be
-    returned. For regression models, label_idx is ignored.
+    starts from 1, while label_idx starts from 0. If feat_idx is not in the
+    valid range (1 to nr_feature), then a zero value will be returned. For
+    classification models, if label_idx is not in the valid range (0 to
+    nr_class-1), then a zero value will be returned; for regression models,
+    label_idx is ignored.
 
 - Function: double get_decfun_bias(const struct model *model_, int label_idx);
 
-    This function gives the bias term corresponding to the class with the 
-    label_idx. For regression models, label_idx is ignored.
+    This function gives the bias term corresponding to the class with the
+    label_idx. For classification models, if label_idx is not in a valid range
+    (0 to nr_class-1), then a zero value will be returned; for regression
+    models, label_idx is ignored.
 
 - Function: const char *check_parameter(const struct problem *prob,
             const struct parameter *param);
diff --git a/linear.cpp b/linear.cpp
index 52d6700..302e1e1 100644
--- a/linear.cpp
+++ b/linear.cpp
@@ -2767,17 +2767,14 @@ static inline double get_w_value(const struct model *model_, int idx, int label_
 	int solver_type = model_->param.solver_type;
 	const double *w = model_->w;
 
-	if(!check_regression_model(model_) && (label_idx < 0 || label_idx >= nr_class)) 
-	{
-		const double nan = 0.0/0.0;
-		return nan;
-	}
 	if(idx < 0 || idx > model_->nr_feature)
 		return 0;
 	if(check_regression_model(model_))
 		return w[idx];
 	else 
 	{
+		if(label_idx < 0 || label_idx >= nr_class)
+			return 0;
 		if(nr_class == 2 && solver_type != MCSVM_CS)
 		{
 			if(label_idx == 0)