Initial data commit

Task/Arithmetic-derivative/C/arithmetic-derivative.c

@@ -0,0 +1,76 @@
+#include <stdio.h>
+#include <stdint.h>
+
+typedef uint64_t u64;
+
+void primeFactors(u64 n, u64 *factors, int *length) {
+    if (n < 2) return;
+    int count = 0;
+    int inc[8] = {4, 2, 4, 2, 4, 6, 2, 6};
+    while (!(n%2)) {
+        factors[count++] = 2;
+        n /= 2;
+    }
+    while (!(n%3)) {
+        factors[count++] = 3;
+        n /= 3;
+    }
+    while (!(n%5)) {
+        factors[count++] = 5;
+        n /= 5;
+    }
+    for (u64 k = 7, i = 0; k*k <= n; ) {
+        if (!(n%k)) {
+            factors[count++] = k;
+            n /= k;
+        } else {
+            k += inc[i];
+            i = (i + 1) % 8;
+        }
+    }
+    if (n > 1) {
+        factors[count++] = n;
+    }
+    *length = count;
+}
+
+double D(double n) {
+    if (n < 0) return -D(-n);
+    if (n < 2) return 0;
+    int i, length;
+    double d;
+    u64 f[80], g;
+    if (n < 1e19) {
+        primeFactors((u64)n, f, &length);
+    } else {
+        g = (u64)(n / 100);
+        primeFactors(g, f, &length);
+        f[length+1] = f[length] = 2;
+        f[length+3] = f[length+2] = 5;
+        length += 4;
+    }
+    if (length == 1) return 1;
+    if (length == 2) return (double)(f[0] + f[1]);
+    d = n / (double)f[0];
+    return D(d) * (double)f[0] + d;
+}
+
+int main() {
+    u64 ad[200];
+    int n, m;
+    double pow;
+    for (n = -99; n < 101; ++n) {
+        ad[n+99] = (int)D((double)n);
+    }
+    for (n = 0; n < 200; ++n) {
+        printf("%4ld ", ad[n]);
+        if (!((n+1)%10)) printf("\n");
+    }
+    printf("\n");
+    pow = 1;
+    for (m = 1; m < 21; ++m) {
+        pow *= 10;
+        printf("D(10^%-2d) / 7 = %.0f\n", m, D(pow)/7);
+    }
+    return 0;
+}