diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..3d37e57
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,63 @@
+cmake_minimum_required(VERSION 2.8.4)
+
+project(tinyexpr)
+
+option(TE_POW_FROM_RIGHT "Evaluate exponents from right to left." OFF)
+option(TE_NAT_LOG "Define the log function as natural logarithm." OFF)
+option(build_tinyexpr_test "Build TinyExpr tests." OFF)
+option(build_tinyexpr_test_pr "Build TinyExpr tests PR." OFF)
+option(build_tinyexpr_bench "Build TinyExpr benchmark." OFF)
+option(build_tinyexpr_example "Build TinyExpr example." OFF)
+option(build_tinyexpr_example2 "Build TinyExpr example 2." OFF)
+option(build_tinyexpr_example3 "Build TinyExpr example 3." OFF)
+
+find_library(MATH_LIB m)
+
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -ansi -Wall -Wshadow -fPIC -O3")
+
+set(SOURCE_FILES
+        tinyexpr.c
+        tinyexpr.h
+        )
+
+add_library(tinyexpr STATIC ${SOURCE_FILES})
+if (TE_POW_FROM_RIGHT)
+    target_compile_definitions(tinyexpr PRIVATE TE_POW_FROM_RIGHT)
+endif()
+if (TE_NAT_LOG)
+    target_compile_definitions(tinyexpr PRIVATE TE_NAT_LOG)
+endif()
+target_link_libraries(tinyexpr ${MATH_LIB})
+install(TARGETS tinyexpr ARCHIVE DESTINATION lib)
+install(FILES tinyexpr.h DESTINATION include COMPONENT Devel)
+
+if (build_tinyexpr_test)
+    add_executable(tinyexpr_test test.c tinyexpr.c)
+    target_link_libraries(tinyexpr_test ${MATH_LIB})
+endif()
+
+if (build_tinyexpr_test_pr)
+    add_executable(tinyexpr_test_pr test.c tinyexpr.c)
+    target_compile_definitions(tinyexpr_test_pr PRIVATE TE_POW_FROM_RIGHT TE_NAT_LOG)
+    target_link_libraries(tinyexpr_test_pr ${MATH_LIB})
+endif()
+
+if (build_tinyexpr_bench)
+    add_executable(tinyexpr_benchmark benchmark.c tinyexpr.c)
+    target_link_libraries(tinyexpr_benchmark ${MATH_LIB})
+endif()
+
+if (build_tinyexpr_example)
+    add_executable(tinyexpr_example example.c tinyexpr.c)
+    target_link_libraries(tinyexpr_example ${MATH_LIB})
+endif()
+
+if (build_tinyexpr_example2)
+    add_executable(tinyexpr_example2 example2.c tinyexpr.c)
+    target_link_libraries(tinyexpr_example2 ${MATH_LIB})
+endif()
+
+if (build_tinyexpr_example3)
+    add_executable(tinyexpr_example3 example3.c tinyexpr.c)
+    target_link_libraries(tinyexpr_example3 ${MATH_LIB})
+endif()
diff --git a/test.c b/test.c
index c772950..a44628d 100644
--- a/test.c
+++ b/test.c
@@ -672,6 +672,100 @@ void test_combinatorics() {
 }
 
 
+void test_logic() {
+    test_case cases[] = {
+            {"1 && 1", 1},
+            {"1 && 0", 0},
+            {"0 && 1", 0},
+            {"0 && 0", 0},
+            {"1 || 1", 1},
+            {"1 || 0", 1},
+            {"0 || 1", 1},
+            {"0 || 0", 0},
+            {"!0", 1},
+            {"!1", 0},
+            {"!2", 0},
+
+            {"!-2", 0},
+            {"-!2", 0},
+            {"!!0", 0},
+            {"!!1", 1},
+            {"!!2", 1},
+            {"!!-2", 1},
+            {"!-!2", 1},
+            {"-!!2", -1},
+            {"--!!2", 1},
+
+            {"1 < 2", 1},
+            {"2 < 2", 0},
+            {"2 <= 2", 1},
+            {"2 > 1", 1},
+            {"2 > 2", 0},
+            {"2 >= 2", 1},
+            {"2 > -2", 1},
+            {"-2 < 2", 1},
+
+            {"0 == 0", 1},
+            {"0 != 0", 0},
+            {"2 == 2", 1},
+            {"2 != 2", 0},
+            {"2 == 3", 0},
+            {"2 != 3", 1},
+            {"2 == 2.0001", 0},
+            {"2 != 2.0001", 1},
+
+            {"1 < 2 && 2 < 3", 1},
+            {"1 < 2 && 3 < 2", 0},
+            {"2 < 1 && 2 < 3", 0},
+            {"2 < 1 && 3 < 2", 0},
+            {"1 < 2 || 2 < 3", 1},
+            {"1 < 2 || 3 < 2", 1},
+            {"2 < 1 || 2 < 3", 1},
+            {"2 < 1 || 3 < 2", 0},
+
+            {"1 < 1+1", 1},
+            {"1 < 1*2", 1},
+            {"1 < 2/2", 0},
+            {"1 < 2^2", 1},
+
+            {"5+5 < 4+10", 1},
+            {"5+(5 < 4)+10", 15},
+            {"5+(5 < 4+10)", 6},
+            {"(5+5 < 4)+10", 10},
+            {"5+!(5 < 4)+10", 16},
+            {"5+!(5 < 4+10)", 5},
+            {"!(5+5 < 4)+10", 11},
+
+#ifdef TE_POW_FROM_RIGHT
+            {"!0^2", 1},
+            {"!0^-1", 0},
+            {"-!0^2", -1},
+#else
+            {"!0^2", 1},
+            {"!0^-1", 1},
+            {"-!0^2", 1},
+#endif
+
+    };
+
+
+    int i;
+    for (i = 0; i < sizeof(cases) / sizeof(test_case); ++i) {
+        const char *expr = cases[i].expr;
+        const double answer = cases[i].answer;
+
+        int err;
+        const double ev = te_interp(expr, &err);
+        lok(!err);
+        lfequal(ev, answer);
+
+        if (err) {
+            printf("FAILED: %s (%d)\n", expr, err);
+        }
+    }
+}
+
+
 int main(int argc, char *argv[])
 {
     lrun("Results", test_results);
@@ -685,6 +779,7 @@ int main(int argc, char *argv[])
     lrun("Optimize", test_optimize);
     lrun("Pow", test_pow);
     lrun("Combinatorics", test_combinatorics);
+    lrun("Logic", test_logic);
     lresults();
 
     return lfails != 0;
diff --git a/tinyexpr.c b/tinyexpr.c
index 91a1848..f61869c 100755
--- a/tinyexpr.c
+++ b/tinyexpr.c
@@ -225,6 +225,19 @@ static double divide(double a, double b) {return a / b;}
 static double negate(double a) {return -a;}
 static double comma(double a, double b) {(void)a; return b;}
 
+static double greater(double a, double b) {return a > b;}
+static double greater_eq(double a, double b) {return a >= b;}
+static double lower(double a, double b) {return a < b;}
+static double lower_eq(double a, double b) {return a <= b;}
+static double equal(double a, double b) {return a == b;}
+static double not_equal(double a, double b) {return a != b;}
+static double logical_and(double a, double b) {return a != 0.0 && b != 0.0;}
+static double logical_or(double a, double b) {return a != 0.0 || b != 0.0;}
+static double logical_not(double a) {return a == 0.0;}
+static double logical_notnot(double a) {return a != 0.0;}
+static double negate_logical_not(double a) {return -(a == 0.0);}
+static double negate_logical_notnot(double a) {return -(a != 0.0);}
+
 
 void next_token(state *s) {
     s->type = TOK_NULL;
@@ -281,6 +294,51 @@ void next_token(state *s) {
                     case '/': s->type = TOK_INFIX; s->function = divide; break;
                     case '^': s->type = TOK_INFIX; s->function = pow; break;
                     case '%': s->type = TOK_INFIX; s->function = fmod; break;
+                    case '!':
+                        if (s->next++[0] == '=') {
+                            s->type = TOK_INFIX; s->function = not_equal;
+                        } else {
+                            s->next--;
+                            s->type = TOK_INFIX; s->function = logical_not;
+                        }
+                        break;
+                    case '=':
+                        if (s->next++[0] == '=') {
+                            s->type = TOK_INFIX; s->function = equal;
+                        } else {
+                            s->type = TOK_ERROR;
+                        }
+                        break;
+                    case '<':
+                        if (s->next++[0] == '=') {
+                            s->type = TOK_INFIX; s->function = lower_eq;
+                        } else {
+                            s->next--;
+                            s->type = TOK_INFIX; s->function = lower;
+                        }
+                        break;
+                    case '>':
+                        if (s->next++[0] == '=') {
+                            s->type = TOK_INFIX; s->function = greater_eq;
+                        } else {
+                            s->next--;
+                            s->type = TOK_INFIX; s->function = greater;
+                        }
+                        break;
+                    case '&':
+                        if (s->next++[0] == '&') {
+                            s->type = TOK_INFIX; s->function = logical_and;
+                        } else {
+                            s->type = TOK_ERROR;
+                        }
+                        break;
+                    case '|':
+                        if (s->next++[0] == '|') {
+                            s->type = TOK_INFIX; s->function = logical_or;
+                        } else {
+                            s->type = TOK_ERROR;
+                        }
+                        break;
                     case '(': s->type = TOK_OPEN; break;
                     case ')': s->type = TOK_CLOSE; break;
                     case ',': s->type = TOK_SEP; break;
@@ -393,20 +451,48 @@ static te_expr *base(state *s) {
 
 
 static te_expr *power(state *s) {
-    /* <power>     =    {("-" | "+")} <base> */
+    /* <power>     =    {("-" | "+" | "!")} <base> */
     int sign = 1;
     while (s->type == TOK_INFIX && (s->function == add || s->function == sub)) {
         if (s->function == sub) sign = -sign;
         next_token(s);
     }
 
+    int logical = 0;
+    while (s->type == TOK_INFIX && (s->function == add || s->function == sub || s->function == logical_not)) {
+        if (s->function == logical_not) {
+            if (logical == 0) {
+                logical = -1;
+            } else {
+                logical = -logical;
+            }
+        }
+        next_token(s);
+    }
+
     te_expr *ret;
 
     if (sign == 1) {
-        ret = base(s);
+        if (logical == 0) {
+            ret = base(s);
+        } else if (logical == -1) {
+            ret = NEW_EXPR(TE_FUNCTION1 | TE_FLAG_PURE, base(s));
+            ret->function = logical_not;
+        } else {
+            ret = NEW_EXPR(TE_FUNCTION1 | TE_FLAG_PURE, base(s));
+            ret->function = logical_notnot;
+        }
     } else {
-        ret = NEW_EXPR(TE_FUNCTION1 | TE_FLAG_PURE, base(s));
-        ret->function = negate;
+        if (logical == 0) {
+            ret = NEW_EXPR(TE_FUNCTION1 | TE_FLAG_PURE, base(s));
+            ret->function = negate;
+        } else if (logical == -1) {
+            ret = NEW_EXPR(TE_FUNCTION1 | TE_FLAG_PURE, base(s));
+            ret->function = negate_logical_not;
+        } else {
+            ret = NEW_EXPR(TE_FUNCTION1 | TE_FLAG_PURE, base(s));
+            ret->function = negate_logical_notnot;
+        }
     }
 
     return ret;
@@ -417,14 +503,16 @@ static te_expr *factor(state *s) {
     /* <factor>    =    <power> {"^" <power>} */
     te_expr *ret = power(s);
 
-    int neg = 0;
+    const void *left_function = NULL;
     te_expr *insertion = 0;
 
-    if (ret->type == (TE_FUNCTION1 | TE_FLAG_PURE) && ret->function == negate) {
+    if (ret->type == (TE_FUNCTION1 | TE_FLAG_PURE) &&
+        (ret->function == negate || ret->function == logical_not || ret->function == logical_notnot ||
+        ret->function == negate_logical_not || ret->function == negate_logical_notnot)) {
+        left_function = ret->function;
         te_expr *se = ret->parameters[0];
         free(ret);
         ret = se;
-        neg = 1;
     }
 
     while (s->type == TOK_INFIX && (s->function == pow)) {
@@ -444,9 +532,9 @@ static te_expr *factor(state *s) {
         }
     }
 
-    if (neg) {
+    if (left_function) {
         ret = NEW_EXPR(TE_FUNCTION1 | TE_FLAG_PURE, ret);
-        ret->function = negate;
+        ret->function = left_function;
     }
 
     return ret;
@@ -484,7 +572,7 @@ static te_expr *term(state *s) {
 }
 
 
-static te_expr *expr(state *s) {
+static te_expr *sum_expr(state *s) {
     /* <expr>      =    <term> {("+" | "-") <term>} */
     te_expr *ret = term(s);
 
@@ -499,6 +587,37 @@ static te_expr *expr(state *s) {
 }
 
 
+static te_expr *test_expr(state *s) {
+    /* <expr>      =    <sum_expr> {(">" | ">=" | "<" | "<=" | "==" | "!=") <sum_expr>} */
+    te_expr *ret = sum_expr(s);
+
+    while (s->type == TOK_INFIX && (s->function == greater || s->function == greater_eq ||
+        s->function == lower || s->function == lower_eq || s->function == equal || s->function == not_equal)) {
+        te_fun2 t = s->function;
+        next_token(s);
+        ret = NEW_EXPR(TE_FUNCTION2 | TE_FLAG_PURE, ret, sum_expr(s));
+        ret->function = t;
+    }
+
+    return ret;
+}
+
+
+static te_expr *expr(state *s) {
+    /* <expr>      =    <test_expr> {("&&" | "||") <test_expr>} */
+    te_expr *ret = test_expr(s);
+
+    while (s->type == TOK_INFIX && (s->function == logical_and || s->function == logical_or)) {
+        te_fun2 t = s->function;
+        next_token(s);
+        ret = NEW_EXPR(TE_FUNCTION2 | TE_FLAG_PURE, ret, test_expr(s));
+        ret->function = t;
+    }
+
+    return ret;
+}
+
+
 static te_expr *list(state *s) {
     /* <list>      =    <expr> {"," <expr>} */
     te_expr *ret = expr(s);