added mod, sin, exp function

CMakeLists.txt

@@ -0,0 +1,6 @@
+cmake_minimum_required(VERSION 3.25)
+project(common_math C)
+
+set(CMAKE_C_STANDARD 11)
+
+add_library(common_math library.c)

library.c

@@ -0,0 +1,75 @@
+#include "library.h"
+
+long long fac(const long long x) {
+    long long prod = 1;
+    for (long long i = 2; i <= x; i++) {
+        prod *= i;
+    }
+    return prod;
+}
+
+inline float trunc(const float x) {
+    return (float)(int)(x);
+}
+
+inline float fract(const float x) {
+    return x - trunc(x);
+}
+
+inline float floor(const float x) {
+    return trunc(x);
+}
+
+inline float ceil(const float x) {
+    return trunc(x + 1);
+}
+
+inline float round(const float x) {
+    return trunc(x + 0.5f);
+}
+
+inline float mod(const float x, const float y) {
+    const float xs = x/y;
+    return (xs - floor(xs)) * 4;
+}
+
+float exp(const float x) {
+    float sum = 0;
+    // iterative counter for computing x^i
+    float xpown = 1;
+    // iterative counter for factorial operation i!
+    float prod = 1;
+
+    // iterate taylor series
+    for (int i = 1; i < TAYLOR_SERIES_DEGREE; i++) {
+        prod *= (float) i;
+        sum += xpown / prod;
+        xpown *= x;
+    }
+    return sum;
+}
+
+float sin(const float x) {
+    float sign = -1;
+    float prod = 1;
+    float xpown = mod(x, 2 * PI);
+    float sum = 0;
+
+    for (int i = 1; i < TAYLOR_SERIES_DEGREE; i++) {
+        sign *= -1;
+        prod *= (float) i * (float) (i - 1);
+        xpown *= x * x;
+
+        sum += sign * xpown / prod;
+    }
+
+    return sum;
+}
+
+inline float cos(const float x) {
+    return sin(x + PI * 0.5f);
+}
+
+inline float tan(const float x) {
+    return sin(x)/cos(x);
+}

library.h

@@ -0,0 +1,97 @@
+#ifndef COMMON_MATH_LIBRARY_H
+#define COMMON_MATH_LIBRARY_H
+
+#define TAYLOR_SERIES_DEGREE 34
+
+const float PI = 3.1415926535897932384626433f;
+
+/**
+ * Compute the factorial of parameter x.
+ * This function only properly works on natural numbers.
+ * The implementation is an iterative one and is only limited by the size
+ * of the type used in the calculation.
+ * @param x the factorial of x or 1 if x < 0
+ * @return the factorial for x
+ */
+long long fac(long long x);
+
+/**
+ * Truncates the parameter x.
+ * In other words this function will cut of the fraction part of the number x.
+ * @param x
+ * @return trunc(x)
+ */
+inline float trunc(float x);
+
+/**
+ * Computes the fraction of x.
+ * In other words this function will only keep the fractional part and cut of the integral.
+ * @param x
+ * @return fract(x)
+ */
+inline float fract(float x);
+
+/**
+ * Computes the floor of x.
+ * In other words this function will round x towards negative infinity.
+ * This is effectively the same as trunc(x)
+ * @param x
+ * @return floor(x)
+ */
+inline float floor(float x);
+
+/**
+ * Computes the ceil of x.
+ * In other words this function will round x towards positive infinity
+ * @param x
+ * @return ceil(x)
+ */
+inline float ceil(float x);
+
+/**
+ * Round the number x.
+ * In other words this function will round x towards negative infinity if x the fraction of x is smaller than 0.5 and else
+ * towards positive infinity
+ * @param x
+ * @return round(x)
+ */
+inline float round(float x);
+
+/**
+ * Compute the modulo division of x and y.
+ * @param x
+ * @param y
+ * @return mod(x,y)
+ */
+float mod(float x, float y);
+
+/**
+ * Computes the result of e raised to the power of x.
+ * This function only performs an approximation based on the famous taylor series for e^x.
+ * @param x the exponent of e^x
+ * @return approximation of e^x
+ */
+float exp(float x);
+
+/**
+ * Computes the sine of x.
+ * @param x
+ * @return sin(x)
+ */
+float sin(float x);
+
+/**
+ * Computes the cosine of x.
+ * @param x
+ * @return cos(x)
+ */
+float cos(float x);
+
+/**
+ * Computes the tangent of x.
+ * @param x
+ * @return tan(x)
+ */
+float tan(float x);
+
+#endif //COMMON_MATH_LIBRARY_H