Wow, maths functions!

math/log.c

@@ -0,0 +1,21 @@
+#include <math.h>
+
+double _agm(double x, double y) {
+  double a = x;
+  double g = y;
+  double temp;
+
+  for(int i = 0; i < 15; i++) {
+    temp = 0.5 * (a + g);
+    g = sqrt(a * g);
+    a = temp;
+  }
+
+  return a;
+}
+
+double log(double x) {
+  double s = x * exp2(24);
+  double nat_log = (M_PI / (2 * _agm(1, 4/s))) - (24 * M_LN2);
+  return nat_log;
+}

math/pow.c

@@ -0,0 +1,5 @@
+#include <math.h>
+
+double pow(double x, double y) {
+  return exp(y * log(x));
+}

math/sqrt.c

@@ -0,0 +1,26 @@
+#include <math.h>
+
+typedef union {
+  double d;
+  struct {
+    unsigned long int mantissa : 52;
+    unsigned int exponent : 11;
+    unsigned int sign_bit : 1;
+  } parts;
+} _dbl_cast;
+
+double sqrt(double x) {
+  _dbl_cast S = { .d = x };
+  double estimate = (0.5 + 0.5 * S.parts.mantissa) *
+    exp2(S.parts.exponent - 1023);
+
+  double a_n, b_n;
+
+  for(int i = 0; i < 15; i++) {
+    a_n = (x - (estimate * estimate)) / (2 * estimate);
+    b_n = estimate + a_n;
+    estimate = b_n - ((a_n * a_n) / (2 * b_n));
+  }
+
+  return estimate;
+}