diff --git a/.gitignore b/.gitignore
index f29cd6b..047802d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 ./main
 ./test
 main
+bin/*
diff --git a/Makefile b/Makefile
index ad9abfa..3d3f42d 100644
--- a/Makefile
+++ b/Makefile
@@ -2,5 +2,11 @@ WERROR?=
 CFLAGS=-Wall -Wextra $(WERROR) -pedantic -I.
 CXXFLAGS_WITHOUT_PKGS=$(CFLAGS) -fno-exceptions -Wno-missing-braces -Wswitch-enum -lm
 
+TEST_SRCS_ENC := $(foreach DIR,src,$(patsubst $(DIR)/%,%,$(wildcard ./src/*.c)))
+TEST_SRCS_ENC := $(filter-out %main.c, $(TEST_SRCS_ENC))
+
 build:
-	gcc src/* -o ./main ${CXXFLAGS_WITHOUT_PKGS}
+	gcc src/* -o ./bin/main ${CXXFLAGS_WITHOUT_PKGS}
+test:
+	gcc ${TEST_SRCS_ENC} ./tests/* -o ./bin/test ${CXXFLAGS_WITHOUT_PKGS}
+	./bin/test
diff --git a/src/evaluator.c b/src/evaluator.c
index c7172e0..713c1f5 100644
--- a/src/evaluator.c
+++ b/src/evaluator.c
@@ -69,6 +69,59 @@ int evaluator_reduce_operator_pattern(struct List* evalList) {
     return 0;
 }
 
+/**
+This sub script will look for pattern like Operator (minus sign) Number
+and evaluate that
+*/
+int evaluator_reduce_minus_pattern(struct List* evalList) {
+    int patternPos = -1;
+    for (int i = 0; i < evalList->num_elements; i++) {
+        if (
+            ((i >= 1 && !is_type_number(list_get_type(evalList, i-1))) || (i == 0)) &&
+            list_get_type(evalList, i) == TYPE_OPERATOR &&
+            is_type_number(list_get_type(evalList, i+1))
+        ) {
+            char candidateOperator;
+            list_get(evalList, i, &candidateOperator);
+            if (candidateOperator != '-') {
+                continue;
+            }
+
+            patternPos = i;
+            break;
+        }
+    }
+
+    if (patternPos == -1) {
+        // we did not find anything to reduce we return negative
+        return -1;
+    }
+    // we found a positive pattern, we gonna reduce
+    int type = list_get_type(evalList, patternPos+1);
+    int val;
+    list_get(evalList, patternPos+1, &val);
+    
+    int res = 0;
+    unsigned char typeRes = 0;
+    int operateStatus = operate('*', TYPE_INT, -1, type, val, &typeRes, &res);
+    if (operateStatus != 0) {
+        printf("ERR Evaluator: cannot operate \n");
+        return 400;
+    }
+
+    if (typeRes == TYPE_INT) {
+        list_set(evalList, patternPos, TYPE_INT, &res);
+    }
+    if (typeRes == TYPE_FLOAT) {
+        // FIXME: invalid type set, we need to flag for float
+        list_set(evalList, patternPos, TYPE_FLOAT, &res);
+    }
+
+    list_delete(evalList, patternPos+1);
+
+    return 0;
+}
+
 
 /**
 This sub script will look for pattern like ({Number})
@@ -78,6 +131,7 @@ int evaluator_reduce_parenthesis_pattern(struct List* evalList) {
     int patternPos = -1;
     for (int i = 0; i < evalList->num_elements; i++) {
         if (
+            ((i >= 1 && list_get_type(evalList, i-1) != TYPE_FUNC_NAME) || (i == 0)) &&
             list_get_type(evalList, i) == TYPE_OPEN_PARENTHESIS &&
             is_type_number(list_get_type(evalList, i+1)) &&
             list_get_type(evalList, i+2) == TYPE_CLOSE_PARENTHESIS
@@ -118,26 +172,13 @@ if we don't find that, we throw an error
 int evaluator_reduce_function_call(struct List* evalList) {
     int patternPos = -1;
 
-    short argsLen = 0;
     for (int i = 0; i < evalList->num_elements; i++) {
-        if (
-            (list_get_type(evalList, i) == TYPE_FUNC_NAME &&
-            list_get_type(evalList, i+1) == TYPE_OPEN_PARENTHESIS &&
-            is_type_number(list_get_type(evalList, i+2)))
-        ) {
-            // mode: we have at least one argument
-            patternPos = i;
-            argsLen = 1;
-            break;
-        }
         if (
             list_get_type(evalList, i) == TYPE_FUNC_NAME &&
-            list_get_type(evalList, i+1) == TYPE_OPEN_PARENTHESIS &&
-            list_get_type(evalList, i+2) == TYPE_CLOSE_PARENTHESIS
+            list_get_type(evalList, i+1) == TYPE_OPEN_PARENTHESIS
         ) {
-            // special mode: functions call with no arguments
+            // mode: we have a function call
             patternPos = i;
-            argsLen = 0;
             break;
         }
     }
@@ -151,39 +192,54 @@ int evaluator_reduce_function_call(struct List* evalList) {
     // fetch the function ID
     list_get(evalList, patternPos, &funcID);
 
+    short argsLen = 0;
     int pos = patternPos+2;
-    if (argsLen > 0) {
-        // now we know we have a start of a function
-        // we gonna start to look if there is others arguments
-        // two case: either we have another arguments or we have a closing parenthesis
-        pos = patternPos+3;
-        while (1) {
-            if (argsLen > 16) {
-                printf("ERR Evaluator: too many arguments passed to func \n");
-                return 100;
-            }
-            if (
-                list_get_type(evalList, pos) == TYPE_COMMA &&
-                is_type_number(list_get_type(evalList, pos+1))
-            ) {
-                // another argument
-                pos += 2;
-                argsLen++;
-                continue;
-            }
-            if (
-                (
-                    list_get_type(evalList, pos) == TYPE_COMMA &&
-                    list_get_type(evalList, pos+1) == TYPE_CLOSE_PARENTHESIS
-                ) || (list_get_type(evalList, pos) == TYPE_CLOSE_PARENTHESIS)
-            ) {
-                // we close the function call
-                break;
-            }
 
-            printf("ERR Evaluator: cannot reduce function call \n");
+    // now we know we have a start of a function
+    // we gonna start to look if there is others arguments
+    // two case: either we have another arguments or we have a closing parenthesis
+    while (1) {
+        if (argsLen > 16) {
+            printf("ERR Evaluator: too many arguments passed to func (max out the limit) \n");
             return 100;
         }
+        if (
+            list_get_type(evalList, pos) == TYPE_CLOSE_PARENTHESIS
+        ) {
+            // end of the function call
+            pos += 0;
+            break;
+        }
+        if (
+            list_get_type(evalList, pos) == TYPE_COMMA &&
+            list_get_type(evalList, pos+1) == TYPE_CLOSE_PARENTHESIS
+        ) {
+            // end of the function call
+            pos += 1;
+            break;
+        }
+        
+        if (
+            is_type_number(list_get_type(evalList, pos)) &&
+            list_get_type(evalList, pos+1) == TYPE_COMMA
+        ) {
+            // this is a new argument
+            pos += 2;
+            argsLen++;
+            continue;
+        }
+        if (
+            is_type_number(list_get_type(evalList, pos)) &&
+            list_get_type(evalList, pos+1) == TYPE_CLOSE_PARENTHESIS
+        ) {
+            // we didn't match the last pattern so it's the last argument
+            pos += 1;
+            argsLen++;
+            continue;
+        }
+
+        // we cannot reduce more, it's probably because the func call is not ready to be reduced, meaning that the arguments need to be evaluated
+        return -1;
     }
     // now pos is the index of the last component for this func call
 
@@ -209,13 +265,18 @@ int evaluator_reduce_function_call(struct List* evalList) {
     // now we can delete in the list from pos+1 patternPos to pos
     // just delete N-1 times where N is the number of components in the func call
     //printf("start: %d, end: %d \n", patternPos, pos);
-
+    //printf("patternPos: %d, pos: %d \n", patternPos, pos);
     for (int j = 0; j < (pos-patternPos); j++) {
         list_delete(evalList, patternPos);
     }
 
+    //printf("list report after deleting after applying a func \n");
+    //list_print(evalList);
+
+    //printf("patternPos: %d, resType: %d \n", patternPos, resType);
     list_set(evalList, patternPos, resType, &resVal);
 
+
     return 0;
 }
 
@@ -226,7 +287,7 @@ Arguments:
 - Input String: char pointer (the source of the evaluation)
 - Result: int pointer (where the result of the evaluation will be written)
 */
-int evaluate(char* inputStr, int* resultPtr, int* typePtr) {
+int evaluate(char* inputStr, int* resultPtr, unsigned char* typePtr) {
     int i = 0;
     int _len = strlen(inputStr);
     // we want first to parse the expression and create a stack
@@ -315,19 +376,55 @@ int evaluate(char* inputStr, int* resultPtr, int* typePtr) {
     }
 
     struct List evalList;
+    // NOTICE: for some reason the struct don't reset after a usage
+    list_reset(&evalList);
     printf("\n - constructing list \n");
     // initializing the evaluation list
     for (int j = 0; j < partitionPtr; j++) {
-        int len = partitionStopPos[j] - partitionStartPos[j];
+
+        int startPos = partitionStartPos[j];
+        int stopPos = partitionStopPos[j];
+        printf("=== %d\n", j);
+        printf("startPos %d, stopPos %d\n", startPos, stopPos);
+        int len = stopPos - startPos;
+
+        // modifiy the start and stop pos to trim spaces
+        int startTrimOffset = 0;
+        int stopTrimOffset = 0;
+        for (int z = 0; z < len; z++) {
+            if (inputStr[startPos+z] != ' ') {
+                break;
+            }
+            startTrimOffset++;
+        }
+        for (int z = 1; z < len; z++) {
+            if (inputStr[stopPos-z] != ' ') {
+                break;
+            }
+            stopTrimOffset++;
+        }
+        startPos += startTrimOffset;
+        stopPos -= stopTrimOffset;
+        
+        len = stopPos - startPos;
         char buff[_len+1];
+        buff[0] = 0;
+
         // fill the buffer with the component string
         for (int z = 0; z < len; z++) {
-            buff[z] = inputStr[partitionStartPos[j]+z];
+            buff[z] = inputStr[startPos+z];
         }
+        buff[len] = 0; // terminate the buff
 
         // TODO: SPLIT INTO A FUNCTION "identify_token(char* str)"
-        buff[len] = 0;
+        
+        printf("buff: '%s' \n", buff);
+        
         char dumbValue = (char) 0;
+
+        if (buff[0] == '\0') {
+            continue;
+        }
         if (len == 1 && buff[0] == '(') {
             list_set(&evalList, evalList.num_elements, TYPE_OPEN_PARENTHESIS, &dumbValue);
             continue;
@@ -341,11 +438,12 @@ int evaluate(char* inputStr, int* resultPtr, int* typePtr) {
             continue;
         }
         if (len == 1 && is_operator(buff[0])) {
+            printf("found op\n");
             char opValue = buff[0];
             list_set(&evalList, evalList.num_elements, TYPE_OPERATOR, &opValue);
             continue;
         }
-        
+
         int res = 0;
         int st = parse_int(buff, &res);
         if (st == 0) {
@@ -374,6 +472,7 @@ int evaluate(char* inputStr, int* resultPtr, int* typePtr) {
                 list_set(&evalList, evalList.num_elements, TYPE_FUNC_NAME, &funcID);
             }
         }
+        printf("end of l\n");
     }
 
     // check the content of this thing
@@ -383,10 +482,10 @@ int evaluate(char* inputStr, int* resultPtr, int* typePtr) {
     while (evalList.num_elements > 1) {
         list_print(&evalList);
 
-        // we are going to look for pattern 
-        // - 0. OPENP NUM CLOSEP
-        // - 1. NUM OP NUM
+        // we are going to look for pattern to reduce
+        // the order is really important here
         int reduceFuncOpStat = evaluator_reduce_function_call(&evalList);
+        int reduceMinusOpStat = evaluator_reduce_minus_pattern(&evalList);
         int reduceOperatorOpStat = evaluator_reduce_operator_pattern(&evalList);
         int reduceParenthesisOpStat = evaluator_reduce_parenthesis_pattern(&evalList);
         
@@ -401,7 +500,12 @@ int evaluate(char* inputStr, int* resultPtr, int* typePtr) {
             return reduceOperatorOpStat;
         }
 
-        if (reduceFuncOpStat == -1 && reduceOperatorOpStat == -1 && reduceParenthesisOpStat == -1) {
+        if (
+            reduceFuncOpStat == -1 &&
+            reduceOperatorOpStat == -1 &&
+            reduceParenthesisOpStat == -1 &&
+            reduceMinusOpStat == -1
+        ) {
             // all scans failed to find things to reduce
             // this is actually a failure because we can't do anything to get down to 1 element in the eval list
             printf("ERR Evaluator: could not reduce more, dumping evalList: \n");
diff --git a/src/evaluator.h b/src/evaluator.h
index 9356b0b..0e41e9a 100644
--- a/src/evaluator.h
+++ b/src/evaluator.h
@@ -1,6 +1,6 @@
 #ifndef EVALUATOR_H_
 #define EVALUATOR_H_
 
-int evaluate(char* inputStr, int* resultPtr, int* typePtr);
+int evaluate(char* inputStr, int* resultPtr, unsigned char* typePtr);
 
 #endif
diff --git a/src/funcs.c b/src/funcs.c
index 21f06d3..52144d9 100644
--- a/src/funcs.c
+++ b/src/funcs.c
@@ -2,16 +2,15 @@
 #include <string.h>
 #include <math.h>
 #include "./types.h"
-#include "./repr_utils.h"
+#include "./utils.h"
 
 int abs_implementation(int* res, unsigned char* resType, unsigned char* types, int* args)
 {
     if (types[0] == TYPE_INT) {
+        *res = args[0];
         if (args[0] < 0) {
             *res = -args[0];
-            return 0;
         }
-        *res = args[0];
         *resType = TYPE_INT;
         return 0;
     }
@@ -73,7 +72,7 @@ int max_implementation(int* res, unsigned char* resType, unsigned char* types, i
 
 int get_pi_implementation(int* res, unsigned char* resType, unsigned char* types, int* args)
 {
-    float val = 3.1415926535;
+    float val = CST_PI;
     *res = *(int *)(&val);
     *resType = TYPE_FLOAT;
     return 0;
@@ -88,10 +87,10 @@ struct FuncIntro {
 // void* are actually long!
 
 struct FuncIntro intros[] = {
-    {"ABS", &abs_implementation, 1},
-    {"SQRT", &sqrt_implementation, 1},
-    {"MAX", &max_implementation, 2},
-    {"GET_PI", &get_pi_implementation, 0},
+    {"abs", &abs_implementation, 1},
+    {"sqrt", &sqrt_implementation, 1},
+    {"max", &max_implementation, 2},
+    {"get_pi", &get_pi_implementation, 0},
     {"", 0, 0}
 };
 
@@ -135,7 +134,13 @@ int execute_func(short funcID, short argsLen, unsigned char* argsTypes, int* arg
     // call the function implementation
     // first cast the function ptr
     impl(resPtr, resTypePtr, argsTypes, argsValues);
-    printf("Got %d \n", *resPtr);
+    if (*resTypePtr == TYPE_FLOAT) {
+        printf("Got TYPE_FLOAT with val: %f \n", get_float_from_int_rep(*resPtr));
+    } else if (*resTypePtr == TYPE_INT) {
+        printf("Got TYPE_INT with val: %d \n", *resPtr);
+    } else {
+        printf("Got WTF NOTHING (%d) with val: %d \n", *resTypePtr, *resPtr);
+    }
 
     return 0;
 }
diff --git a/src/list.c b/src/list.c
index 65e92ca..b8d1b31 100644
--- a/src/list.c
+++ b/src/list.c
@@ -194,6 +194,15 @@ int list_delete(struct List* list, int index)
     return 0;
 }
 
+void list_reset(struct List* list)
+{
+    for (int i = 0; i < list->num_elements; i++) {
+        list_delete(list, 0);
+    }
+    list->data_ptr = 0;
+    list->bytes_used = 0;
+    list->num_elements = 0;
+}
 
 int list_append_int(struct List* list, int value)
 {
diff --git a/src/list.h b/src/list.h
index f34d23d..6e06070 100644
--- a/src/list.h
+++ b/src/list.h
@@ -68,4 +68,6 @@ int list_delete(struct List* list, int index);
 
 void list_print(struct List*);
 
+void list_reset(struct List* list);
+
 #endif
diff --git a/src/main.c b/src/main.c
index bb195ab..951bbdf 100644
--- a/src/main.c
+++ b/src/main.c
@@ -5,7 +5,7 @@
 #include "./list.h"
 #include "./number_parsing.h"
 #include "./evaluator.h"
-#include "./repr_utils.h"
+#include "./utils.h"
 #include "./types.h"
 //int create_stack(int a, int b)
 
diff --git a/src/number_parsing.c b/src/number_parsing.c
index fd047cd..13fd306 100644
--- a/src/number_parsing.c
+++ b/src/number_parsing.c
@@ -1,29 +1,7 @@
 #include <stdio.h>
 #include <string.h>
 #include "./number_parsing.h"
-
-int is_char_numeral(char candidate) {
-    int n = (int) candidate;
-    return (n >= 48 && n <= 57);
-}
-
-int integer_pow(int base, int exponent)
-{
-    if (exponent == 0) return 1;
-    int r = 1;
-    int multiplier = base;
-    while (exponent) {
-        // if exponent is even
-        if (exponent & 1) {
-            r *= multiplier;
-        }
-
-        multiplier *= multiplier;
-        exponent >>= 1; // divide by two the exponent
-    }
-
-    return r; 
-}
+#include "./utils.h"
 
 int parse_clean_positive_integer(int inputStrLen, char* inputStr, int* result) {
     /**
@@ -152,8 +130,8 @@ int parse_float(char* inputStr, float* resultPtr) {
     }
     cleanStrIntPart[cleanStrIntPartLen] = 0;
     cleanStrFloatPart[cleanStrFloatPartLen] = 0;
-    printf("clean str int part: /%s/ \n", cleanStrIntPart);
-    printf("clean str float part: /%s/ \n", cleanStrFloatPart);
+    // printf("clean str int part: /%s/ \n", cleanStrIntPart);
+    // printf("clean str float part: /%s/ \n", cleanStrFloatPart);
 
     int intPart = 0;
     parse_clean_positive_integer(cleanStrIntPartLen, cleanStrIntPart, &intPart);
diff --git a/src/operate.c b/src/operate.c
index 6b9368c..5dc34f0 100644
--- a/src/operate.c
+++ b/src/operate.c
@@ -1,14 +1,16 @@
-#include "./operate.h"
-#include "./types.h"
 #include <stdio.h>
 #include <string.h>
+#include "./operate.h"
+#include "./types.h"
+#include "./utils.h"
 
 int is_operator(char candidate) {
     return (
         candidate == '*' ||
         candidate == '/' ||
         candidate == '+' ||
-        candidate == '-'
+        candidate == '-' ||
+        candidate == '^'
     );
 }
 
@@ -49,6 +51,8 @@ int operate(
             res = a*b;
         } else if (operator == '/') {
             res = a/b;
+        } else if (operator == '^') {
+            res = 0;
         } else {
             return 2;
         }
@@ -67,6 +71,8 @@ int operate(
             res = aRepr-bRepr;
         } else if (operator == '*') {
             res = aRepr*bRepr;
+        } else if (operator == '^') {
+            res = integer_pow(aRepr, bRepr);
         } else {
             return 2;
         }
diff --git a/src/repr_utils.c b/src/repr_utils.c
deleted file mode 100644
index 821beb4..0000000
--- a/src/repr_utils.c
+++ /dev/null
@@ -1,23 +0,0 @@
-#include "./repr_utils.h"
-
-int get_int_rep_from_float(float ft)
-{
-    return *(int *)(&ft);
-}
-
-/**
- * Get a single precision floating point from int representation
- * (following IEEE 754)
- */
-float get_float_from_int_rep(int representation)
-{
-    float res;
-    *((int*) &res) = representation;
-
-    return res;
-}
-
-int get_int_rep_from_char(char c)
-{
-    return *(int *)(&c);
-}
diff --git a/src/repr_utils.h b/src/repr_utils.h
deleted file mode 100644
index 24e84cf..0000000
--- a/src/repr_utils.h
+++ /dev/null
@@ -1,10 +0,0 @@
-#ifndef REPR_UTILS_H_
-#define REPR_UTILS_H_
-
-int get_int_rep_from_float(float ft);
-
-float get_float_from_int_rep(int representation);
-
-int get_int_rep_from_char(char c);
-
-#endif
diff --git a/src/utils.c b/src/utils.c
new file mode 100644
index 0000000..76f4a90
--- /dev/null
+++ b/src/utils.c
@@ -0,0 +1,255 @@
+#include <stdio.h>
+#include "./utils.h"
+
+int get_int_rep_from_float(float ft)
+{
+    return *(int *)(&ft);
+}
+
+/**
+ * Get a single precision floating point from int representation
+ * (following IEEE 754)
+ */
+float get_float_from_int_rep(int representation)
+{
+    float res;
+    *((int*) &res) = representation;
+
+    return res;
+}
+
+int get_int_rep_from_char(char c)
+{
+    return *(int *)(&c);
+}
+
+int is_char_numeral(char candidate)
+{
+    int n = (int) candidate;
+    return (n >= 48 && n <= 57);
+}
+
+int float_almost_equal(float a, float b)
+{
+    float diff = a-b;
+    if (diff < 0) diff = -diff;
+
+    return diff < 0.001;
+}
+
+int abs_int(int a)
+{
+    return a < 0 ? -a : a;
+}
+
+float abs_float(float a)
+{
+    return a < 0 ? -a : a;
+}
+
+int integer_pow(int base, int exponent)
+{
+    if (exponent == 0) return 1;
+    int r = 1;
+    int multiplier = base;
+    while (exponent) {
+        // if exponent is even
+        if (exponent & 1) {
+            r *= multiplier;
+        }
+
+        multiplier *= multiplier;
+        exponent >>= 1; // divide by two the exponent
+    }
+
+    return r;
+}
+
+float m_float_pow(float base, int exponent)
+{
+    if (exponent == 0) return 1;
+    float r = 1;
+    float multiplier = base;
+    while (exponent) {
+        // if exponent is even
+        if (exponent & 1) {
+            r *= multiplier;
+        }
+
+        multiplier *= multiplier;
+        exponent >>= 1; // divide by two the exponent
+    }
+
+    return r;
+}
+
+int m_factorial(int x)
+{
+    if (x == 0 || x == 1) {
+        return 1;
+    }
+    int res = 1;
+    for (int i = 2; i < x+1; i++) {
+        res *= i;
+    }
+    return res;
+}
+
+float m_exp(float x)
+{
+    const int n = 10;
+    float out = 0;
+    for (int i = 0; i < n; i++) {
+        out += m_float_pow(x, i)/m_factorial(i);
+    }
+    return out;
+}
+
+float m_float_mod(float a, float b)
+{
+    float mod;
+    // Handling negative values
+    if (a < 0)
+        mod = -a;
+    else
+        mod =  a;
+    if (b < 0)
+        b = -b;
+ 
+    // Finding mod by repeated subtraction
+     
+    while (mod >= b)
+        mod = mod - b;
+ 
+    // Sign of result typically depends
+    // on sign of a.
+    if (a < 0)
+        return -mod;
+ 
+    return mod;
+}
+
+float m_sin(float originalX)
+{
+    // use cycles in expension series
+    if (originalX > 2*CST_PI) {
+        originalX = m_float_mod(originalX, (float) (2*CST_PI));
+    }
+    float x = originalX;
+
+    if (originalX > CST_PI) {
+        x -= CST_PI;
+    }
+
+    const int n = 6;
+    float out = 0;
+
+    int sign = 1;
+    for (int i = 0; i < n; i++) {
+        out += sign*(m_float_pow(x, 2*i+1)/m_factorial(2*i+1));
+        
+        if (sign == 1) {
+            sign = -1;
+        } else {
+            sign = 1;
+        }
+    }
+
+    if (originalX > CST_PI) {
+        return -out;
+    }
+    return out;
+}
+
+float m_cos(float x)
+{
+    return m_sin(x+2*CST_PI);
+}
+
+float m_tan(float x)
+{
+    return m_sin(x)/m_cos(x);
+}
+
+// float m_get_derivative(float (*func)(float), float a)
+// {
+//     float h = 0.0001;
+//     return ((func(a+h)-func(a))/h);
+// }
+
+// euler method in one dimension
+// takes a function and find one of the root
+// return the status 0 if success >0 if error
+int m_euler_method(float (*func)(float, float), float param, float startsAt, float* resPtr)
+{
+    // (x-b)f'(b)+f(b) = 0
+    // xf'(b)-bf'(b)+f(b) = 0
+    // x = (-f(b)+bf'(b))/f'(b)
+
+    float cursor = startsAt;
+    float newCursor = 0;
+    float derivative = 0;
+    short runs = 0;
+    const float h = 0.0001;
+    while (1)
+    {
+        derivative = (func(param, cursor+h)-func(param, cursor))/h;
+        newCursor = cursor - func(param, cursor)/derivative;
+        if (abs_float(cursor - newCursor) < 0.0001) {
+            *resPtr = (cursor + newCursor)/2;
+            return 0;
+        }
+        if (runs > 100) {
+            printf("ERR: euler methods failed, coup dur pour euler \n");
+            return 100;
+        }
+        cursor = newCursor;
+        runs++;
+    }
+
+    return 101;
+}
+
+float m_sqrt_equation(float x, float y)
+{
+    return m_float_pow(y,2)-x;
+}
+
+float m_sqrt(float x)
+{
+    float res = 0;
+    m_euler_method(&m_sqrt_equation, x, 4, &res);
+
+    return res;
+}
+
+float m_ln_equation(float x, float y)
+{
+    return m_exp(y)-x;
+}
+
+float m_ln(float x)
+{
+    float res = 0;
+    m_euler_method(&m_ln_equation, x, 4, &res);
+
+    return res;
+}
+
+int is_full_of_space(char* str)
+{
+    int i = 0;
+    while (str[i] != '\0') {
+        if (str[i] != ' ') {
+            return 0;
+        }
+        i++;
+    }
+    return 1;
+}
+
+char* trim_space(char* str)
+{
+    // TODO: implements me
+    return str;
+}
diff --git a/src/utils.h b/src/utils.h
new file mode 100644
index 0000000..05e0767
--- /dev/null
+++ b/src/utils.h
@@ -0,0 +1,38 @@
+#ifndef UTILS_H_
+#define UTILS_H_
+
+#define CST_PI 3.1415926535
+
+int get_int_rep_from_float(float ft);
+
+float get_float_from_int_rep(int representation);
+
+int get_int_rep_from_char(char c);
+
+int is_char_numeral(char candidate);
+
+int integer_pow(int base, int exponent);
+
+int float_almost_equal(float a, float b);
+
+int m_factorial(int x);
+
+float m_float_pow(float base, int exponent);
+
+float m_sqrt(float x);
+
+float m_exp(float x);
+
+float m_ln(float x);
+
+float m_sin(float x);
+
+float m_cos(float x);
+
+float m_tan(float x);
+
+int is_full_of_space(char* str);
+
+char* trim_space(char* str);
+
+#endif
diff --git a/test.c b/test.c
index d60a77b..9fdb52b 100644
--- a/test.c
+++ b/test.c
@@ -3,7 +3,7 @@
 #include "./src/list.h"
 #include "./src/number_parsing.h"
 #include "./src/funcs.h"
-#include "./src/repr_utils.h"
+#include "./src/utils.h"
 
 int some_computation(int a, int b, int* resPtr)
 {
@@ -11,7 +11,16 @@ int some_computation(int a, int b, int* resPtr)
     return 0;
 }
 
+float test_func(float x)
+{
+    return m_float_pow(x,2)-2;
+}
+
 int main () {
+    // test of euler
+    printf("lel : %f \n", m_sqrt(64));
+
+
     // struct List l1;
 
     // list_append_int(&l1, 4);
@@ -33,16 +42,16 @@ int main () {
     // void* ptr = &res;
 
     // printf("%d\n", sizeof(ptr));
-    int found = identify_func_name("ABS");
-    printf("found: %d \n", found);
+    // int found = identify_func_name("ABS");
+    // printf("found: %d \n", found);
 
-    unsigned char argsType[1] = { TYPE_FLOAT };
-    int argsVals[1] = { get_int_rep_from_float(-3.145) };
-    int resVal = 0;
-    unsigned char resType = 0;
-    execute_func(found, 1, argsType, argsVals, &resVal, &resType);
-    printf("func res type: %d \n", resType);
-    printf("func res: %f \n", get_float_from_int_rep(resVal));
+    // unsigned char argsType[1] = { TYPE_FLOAT };
+    // int argsVals[1] = { get_int_rep_from_float(-3.145) };
+    // int resVal = 0;
+    // unsigned char resType = 0;
+    // execute_func(found, 1, argsType, argsVals, &resVal, &resType);
+    // printf("func res type: %d \n", resType);
+    // printf("func res: %f \n", get_float_from_int_rep(resVal));
     
     // int stat = parse_float("1052.254", &res);
     // printf("float parsing stat: %d \n", stat);
diff --git a/tests/test.c b/tests/test.c
new file mode 100644
index 0000000..971cd98
--- /dev/null
+++ b/tests/test.c
@@ -0,0 +1,10 @@
+#include "./test_utils.h"
+#include "./test_evaluation.h"
+#include <stdio.h>
+
+int main()
+{
+    printf("== UNIT TESTS == \n");
+    test_utils();
+    test_evaluation();
+}
diff --git a/tests/test_evaluation.c b/tests/test_evaluation.c
new file mode 100644
index 0000000..ca07a90
--- /dev/null
+++ b/tests/test_evaluation.c
@@ -0,0 +1,60 @@
+#include <stdio.h>
+#include <assert.h>
+#include <string.h>
+#include "../src/types.h"
+#include "../src/number_parsing.h"
+#include "../src/utils.h"
+#include "../src/evaluator.h"
+
+void test_evaluation()
+{
+    printf("== test evaluation == \n");
+
+    // test int parsing
+    int resVal = 0;
+    unsigned char resType = 0;
+
+    evaluate("-4", &resVal, &resType);
+    assert(resType == TYPE_INT);
+    assert(-4 == resVal);
+
+    evaluate("-(4+9)+1", &resVal, &resType);
+    assert(resType == TYPE_INT);
+    assert(-12 == resVal);
+
+    evaluate("(-(8-9+5))+8", &resVal, &resType);
+    assert(resType == TYPE_INT);
+    assert(4 == resVal);
+
+    evaluate("2^6", &resVal, &resType);
+    assert(resType == TYPE_INT);
+    assert(64 == resVal);
+
+    evaluate("3 + 4", &resVal, &resType);
+    assert(resType == TYPE_INT);
+    assert(7 == resVal);
+
+    evaluate("(2*4)+0+0", &resVal, &resType);
+    assert(resType == TYPE_INT);
+    assert(8 == resVal);
+
+    evaluate("2.5-(2+0.1)", &resVal, &resType);
+    assert(resType == TYPE_FLOAT);
+    assert(float_almost_equal(0.4, get_float_from_int_rep(resVal)));
+
+    evaluate("1^0 +  (7*(5 +2))", &resVal, &resType);
+    assert(resType == TYPE_INT);
+    assert(50 == resVal);
+
+    evaluate("- ( 0.1+ 0.3 )", &resVal, &resType);
+    assert(resType == TYPE_FLOAT);
+    assert(float_almost_equal(-0.4, get_float_from_int_rep(resVal)));
+
+    evaluate("sqrt(2)-1", &resVal, &resType);
+    assert(resType == TYPE_FLOAT);
+    assert(float_almost_equal(0.41421, get_float_from_int_rep(resVal)));
+
+    evaluate("(abs((0-1)*2)) + abs(2)", &resVal, &resType);
+    assert(resType == TYPE_INT);
+    assert(4 == resVal);
+}
\ No newline at end of file
diff --git a/tests/test_evaluation.h b/tests/test_evaluation.h
new file mode 100644
index 0000000..5aee13c
--- /dev/null
+++ b/tests/test_evaluation.h
@@ -0,0 +1 @@
+void test_evaluation();
diff --git a/tests/test_utils.c b/tests/test_utils.c
new file mode 100644
index 0000000..7813538
--- /dev/null
+++ b/tests/test_utils.c
@@ -0,0 +1,65 @@
+#include <stdio.h>
+#include <assert.h>
+#include <string.h>
+#include "../src/number_parsing.h"
+#include "../src/utils.h"
+
+void test_utils()
+{
+    printf("== test utils == \n");
+
+    // test int parsing
+    char test1[] = "151087";
+    int res = 0;
+    parse_clean_positive_integer(strlen(test1), test1, &res);
+    assert(res == 151087);
+
+    char test2[] = "-428579";
+    parse_int(test2, &res);
+    assert(res == -428579);
+
+
+    float res3 = 0;
+    char test3[] = "3121.897";
+    parse_float(test3, &res3);
+    assert(float_almost_equal(3121.897, res3));
+
+    float res4 = 0;
+    char test4[] = "-0.4397";
+    parse_float(test4, &res4);
+    assert(float_almost_equal(-0.4397, res4));
+
+    assert(integer_pow(1, 0) == 1);
+    assert(integer_pow(2, 1) == 2);
+    assert(integer_pow(2, 6) == 64);
+
+    assert(m_factorial(0) == 1);
+    assert(m_factorial(1) == 1);
+    assert(m_factorial(2) == 2);
+    assert(m_factorial(3) == 6);
+    assert(m_factorial(4) == 2*3*4);
+
+    assert(float_almost_equal(2.7182, m_exp(1.0)));
+    assert(float_almost_equal(1, m_exp(0)));
+
+    assert(float_almost_equal(0, m_sin(0)));
+    assert(float_almost_equal(1, m_sin(CST_PI/2)));
+    assert(float_almost_equal(0, m_sin(CST_PI)));
+    assert(float_almost_equal(-1, m_sin(3*CST_PI/2)));
+    assert(float_almost_equal(0, m_sin(2*CST_PI)));
+    assert(float_almost_equal(0, m_sin(4*CST_PI)));
+
+    assert(float_almost_equal(1.41421, m_sqrt(2)));
+    assert(float_almost_equal(2.2360, m_sqrt(5)));
+
+    assert(float_almost_equal(0, m_ln(1)));
+    assert(float_almost_equal(1, m_ln(2.7182818)));
+
+    // char src[] = "  hello world  ";
+    // char* trimed = trim_space(src);
+    // assert(strcmp("hello world", trimed) == 0);
+
+    // char src2[] = "hello";
+    // char* trimed2 = trim_space(&src2);
+    // assert(strcmp("hello", trimed2) == 0);
+}
\ No newline at end of file
diff --git a/tests/test_utils.h b/tests/test_utils.h
new file mode 100644
index 0000000..70de024
--- /dev/null
+++ b/tests/test_utils.h
@@ -0,0 +1 @@
+void test_utils();