diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index ba4125bed..548143f58 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -1646,6 +1646,9 @@ bool Tokenizer::tokenize(std::istream &code,
     // replace 'NULL' and similar '0'-defined macros with '0'
     simplifyNull();
 
+    // replace 'sin(0)' to '0' and other similar math expressions
+    simplifyMathExpressions();
+
     // combine "- %num%"
     concatenateNegativeNumber();
 
@@ -9218,6 +9221,32 @@ void Tokenizer::printUnknownTypes()
     }
 }
 
+void Tokenizer::simplifyMathExpressions()
+{
+    for (Token *tok = list.front(); tok; tok = tok->next()) {
+
+        if (Token::Match(tok,"exp ( 0 )") || Token::Match(tok,"cosh ( 0 )") || Token::Match(tok,"cos ( 0 )") || Token::Match(tok,"sqrt ( 1 )")) {
+            tok->deleteNext(3);
+            tok->str("1");
+        }
+
+        if (Token::Match(tok,"sinh ( 0 )") || Token::Match(tok,"sin ( 0 )") || Token::Match(tok,"sqrt ( 0 )") || Token::Match(tok,"ln ( 1 )")) {
+            tok->deleteNext(3);
+            tok->str("0");
+        }
+
+        if (Token::Match(tok,"pow ( sin ( %var% ) , 2 ) + pow ( cos ( %var% ) , 2 )")) {
+            tok->deleteNext(18);
+            tok->str("1");
+        }
+
+        if (Token::Match(tok,"pow ( sinh ( %var% ) , 2 ) - pow ( cosh ( %var% ) , 2 )")) {
+            tok->deleteNext(18);
+            tok->str("-1");
+        }
+    }
+}
+
 const std::string& Tokenizer::getSourceFilePath() const
 {
     if (list.getFiles().empty()) {
diff --git a/lib/tokenize.h b/lib/tokenize.h
index f4f07a334..c15c7947c 100644
--- a/lib/tokenize.h
+++ b/lib/tokenize.h
@@ -461,6 +461,11 @@ public:
      */
     void simplifyMathFunctions();
 
+    /**
+     * Simplify e.g. 'sin(0)' into '0'
+     */
+    void simplifyMathExpressions();
+
     /**
      * Modify strings in the token list by replacing hex and oct
      * values. E.g. "\x61" -> "a" and "\000" -> "\0"
diff --git a/test/testtokenize.cpp b/test/testtokenize.cpp
index 97b864a56..90ebf1212 100644
--- a/test/testtokenize.cpp
+++ b/test/testtokenize.cpp
@@ -439,6 +439,8 @@ private:
         TEST_CASE(platformWin64);
         TEST_CASE(platformUnix32);
         TEST_CASE(platformUnix64);
+
+        TEST_CASE(simplifyMathExpressions); //ticket #1620
     }
 
     std::string tokenizeAndStringify(const char code[], bool simplify = false, bool expand = true, Settings::PlatformType platform = Settings::Unspecified, const char* filename = "test.cpp", bool cpp11 = true) {
@@ -7188,6 +7190,36 @@ private:
 
         ASSERT_EQUALS(expected, tokenizeAndStringify(code, true, true, Settings::Unix64));
     }
+
+    void simplifyMathExpressions() {//#1620
+        const char *code1 ="void foo() {\n"
+                           "std::cout<<sin(0);\n"
+                           "std::cout<<cos(0);\n"
+                           "std::cout<<sinh(0);\n"
+                           "std::cout<<cosh(0);\n"
+                           "std::cout<<exp(0);\n"
+                           "std::cout<<sqrt(0);\n"
+                           "std::cout<<sqrt(1);\n"
+                           "std::cout<<ln(1);\n"
+                           "std::cout<<pow(sin(x),2)+pow(cos(x),2);\n"
+                           "std::cout<<pow(sinh(x),2)-pow(cosh(x),2);\n"
+                           "}";
+
+        const char *expected1 ="void foo ( ) {\n"
+                               "std :: cout << 0 ;\n"
+                               "std :: cout << 1 ;\n"
+                               "std :: cout << 0 ;\n"
+                               "std :: cout << 1 ;\n"
+                               "std :: cout << 1 ;\n"
+                               "std :: cout << 0 ;\n"
+                               "std :: cout << 1 ;\n"
+                               "std :: cout << 0 ;\n"
+                               "std :: cout << 1 ;\n"
+                               "std :: cout << -1 ;\n"
+                               "}";
+        ASSERT_EQUALS(expected1, tokenizeAndStringify(code1));
+    }
+
 };
 
 REGISTER_TEST(TestTokenizer)