diff --git a/source/include/math_helper.h b/source/include/math_helper.h
index 900e08e..65098b3 100644
--- a/source/include/math_helper.h
+++ b/source/include/math_helper.h
@@ -10,6 +10,7 @@
 #ifndef DORAYME_MATH_HELPER_H
 #define DORAYME_MATH_HELPER_H
 
+void set_equal_precision(double v);
 bool double_equal(double a, double b);
 
 #endif //DORAYME_MATH_HELPER_H
diff --git a/source/math_helper.cpp b/source/math_helper.cpp
index b86f2f9..4ce2a0b 100644
--- a/source/math_helper.cpp
+++ b/source/math_helper.cpp
@@ -11,7 +11,14 @@
 #include <float.h>
 #include <math_helper.h>
 
+static double current_precision = FLT_EPSILON;
+
+void set_equal_precision(double v)
+{
+    current_precision = v;
+}
+
 bool double_equal(double a, double b)
 {
-    return fabs(a - b) < DBL_EPSILON;
+    return fabs(a - b) < current_precision;
 }