tasks a-s

Task/Quaternion-type/C/quaternion-type-1.c

@@ -0,0 +1,131 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <math.h>
+
+typedef struct quaternion
+{
+  double q[4];
+} quaternion_t;
+
+
+quaternion_t *quaternion_new(void)
+{
+  return malloc(sizeof(quaternion_t));
+}
+
+quaternion_t *quaternion_new_set(double q1,
+				 double q2,
+				 double q3,
+				 double q4)
+{
+  quaternion_t *q = malloc(sizeof(quaternion_t));
+  if (q != NULL) {
+    q->q[0] = q1; q->q[1] = q2; q->q[2] = q3; q->q[3] = q4;
+  }
+  return q;
+}
+
+
+void quaternion_copy(quaternion_t *r, quaternion_t *q)
+{
+  size_t i;
+
+  if (r == NULL || q == NULL) return;
+  for(i = 0; i < 4; i++) r->q[i] = q->q[i];
+}
+
+
+double quaternion_norm(quaternion_t *q)
+{
+  size_t i;
+  double r = 0.0;
+
+  if (q == NULL) {
+    fprintf(stderr, "NULL quaternion in norm\n");
+    return 0.0;
+  }
+
+  for(i = 0; i < 4; i++) r += q->q[i] * q->q[i];
+  return sqrt(r);
+}
+
+
+void quaternion_neg(quaternion_t *r, quaternion_t *q)
+{
+  size_t i;
+
+  if (q == NULL || r == NULL) return;
+  for(i = 0; i < 4; i++) r->q[i] = -q->q[i];
+}
+
+
+void quaternion_conj(quaternion_t *r, quaternion_t *q)
+{
+  size_t i;
+
+  if (q == NULL || r == NULL) return;
+  r->q[0] = q->q[0];
+  for(i = 1; i < 4; i++) r->q[i] = -q->q[i];
+}
+
+
+void quaternion_add_d(quaternion_t *r, quaternion_t *q, double d)
+{
+  if (q == NULL || r == NULL) return;
+  quaternion_copy(r, q);
+  r->q[0] += d;
+}
+
+
+void quaternion_add(quaternion_t *r, quaternion_t *a, quaternion_t *b)
+{
+  size_t i;
+
+  if (r == NULL || a == NULL || b == NULL) return;
+  for(i = 0; i < 4; i++) r->q[i] = a->q[i] + b->q[i];
+}
+
+
+void quaternion_mul_d(quaternion_t *r, quaternion_t *q, double d)
+{
+  size_t i;
+
+  if (r == NULL || q == NULL) return;
+  for(i = 0; i < 4; i++) r->q[i] = q->q[i] * d;
+}
+
+bool quaternion_equal(quaternion_t *a, quaternion_t *b)
+{
+  size_t i;
+
+  for(i = 0; i < 4; i++) if (a->q[i] != b->q[i]) return false;
+  return true;
+}
+
+
+#define A(N) (a->q[(N)])
+#define B(N) (b->q[(N)])
+#define R(N) (r->q[(N)])
+void quaternion_mul(quaternion_t *r, quaternion_t *a, quaternion_t *b)
+{
+  size_t i;
+  double ri = 0.0;
+
+  if (r == NULL || a == NULL || b == NULL) return;
+  R(0) = A(0)*B(0) - A(1)*B(1) - A(2)*B(2) - A(3)*B(3);
+  R(1) = A(0)*B(1) + A(1)*B(0) + A(2)*B(3) - A(3)*B(2);
+  R(2) = A(0)*B(2) - A(1)*B(3) + A(2)*B(0) + A(3)*B(1);
+  R(3) = A(0)*B(3) + A(1)*B(2) - A(2)*B(1) + A(3)*B(0);
+}
+#undef A
+#undef B
+#undef R
+
+
+void quaternion_print(quaternion_t *q)
+{
+  if (q == NULL) return;
+  printf("(%lf, %lf, %lf, %lf)\n",
+	 q->q[0], q->q[1], q->q[2], q->q[3]);
+}

Task/Quaternion-type/C/quaternion-type-2.c

@@ -0,0 +1,58 @@
+int main()
+{
+  size_t i;
+  double d = 7.0;
+  quaternion_t *q[3];
+  quaternion_t *r  = quaternion_new();
+
+  quaternion_t *qd = quaternion_new_set(7.0, 0.0, 0.0, 0.0);
+  q[0] = quaternion_new_set(1.0, 2.0, 3.0, 4.0);
+  q[1] = quaternion_new_set(2.0, 3.0, 4.0, 5.0);
+  q[2] = quaternion_new_set(3.0, 4.0, 5.0, 6.0);
+
+  printf("r = %lf\n", d);
+
+  for(i = 0; i < 3; i++) {
+    printf("q[%u] = ", i);
+    quaternion_print(q[i]);
+    printf("abs q[%u] = %lf\n", i, quaternion_norm(q[i]));
+  }
+
+  printf("-q[0] = ");
+  quaternion_neg(r, q[0]);
+  quaternion_print(r);
+
+  printf("conj q[0] = ");
+  quaternion_conj(r, q[0]);
+  quaternion_print(r);
+
+  printf("q[1] + q[2] = ");
+  quaternion_add(r, q[1], q[2]);
+  quaternion_print(r);
+
+  printf("q[2] + q[1] = ");
+  quaternion_add(r, q[2], q[1]);
+  quaternion_print(r);
+
+
+  printf("q[0] * r = ");
+  quaternion_mul_d(r, q[0], d);
+  quaternion_print(r);
+
+  printf("q[0] * (r, 0, 0, 0) = ");
+  quaternion_mul(r, q[0], qd);
+  quaternion_print(r);
+
+
+  printf("q[1] * q[2] = ");
+  quaternion_mul(r, q[1], q[2]);
+  quaternion_print(r);
+
+  printf("q[2] * q[1] = ");
+  quaternion_mul(r, q[2], q[1]);
+  quaternion_print(r);
+
+
+  free(q[0]); free(q[1]); free(q[2]); free(r);
+  return EXIT_SUCCESS;
+}