C: sum of multiples + complex numbers

c/complex-numbers/src/complex_numbers.c

@@ -0,0 +1,96 @@
+#include "complex_numbers.h"
+
+#ifdef USE_COMPLEX_FUNCTIONS
+
+complex_t c_add(complex_t a, complex_t b)
+{
+    return (complex_t) {
+        .real = a.real+b.real,
+        .imag = a.imag+b.imag
+    };
+}
+
+complex_t c_sub(complex_t a, complex_t b)
+{
+    return (complex_t) {
+        .real = a.real-b.real,
+        .imag = a.imag-b.imag
+    };
+}
+
+complex_t c_mul(complex_t a, complex_t b)
+{
+    return (complex_t) {
+        .real = a.real*b.real - a.imag*b.imag,
+        .imag = a.imag*b.real + a.real*b.imag,
+    };
+}
+
+complex_t c_div(complex_t a, complex_t b)
+{
+    double d = b.real*b.real + b.imag*b.imag;
+    return (complex_t) {
+        .real = (a.real*b.real + a.imag*b.imag)/d,
+        .imag = (a.imag*b.real - a.real*b.imag)/d
+    };
+}
+
+double c_abs(complex_t x)
+{
+    return sqrt(x.real*x.real + x.imag*x.imag);
+}
+
+complex_t c_conjugate(complex_t x)
+{
+    return (complex_t) {
+        .real = x.real,
+        .imag = -x.imag
+    };
+}
+
+double c_real(complex_t x)
+{
+    return x.real;
+}
+
+double c_imag(complex_t x)
+{
+    return x.imag;
+}
+
+complex_t c_exp(complex_t x)
+{
+    return (complex_t) {
+        .real = exp(x.real)*cos(x.imag),
+        .imag = exp(x.real)*sin(x.imag)
+    };
+}
+
+#endif
+
+/* See GNUmakefile below for explanation
+ * https://github.com/braoult/exercism/blob/master/c/templates/GNUmakefile
+ */
+#ifdef UNIT_TEST
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int ac, char **av)
+{
+    int arg=1;
+    complex_t c1, c2, c3;
+
+    for (; arg<ac-3; ++arg, ++arg) {
+        c1.real=atof(av[arg]);
+        c1.imag=atof(av[arg+1]);
+
+        c2.real=atof(av[arg+2]);
+        c2.imag=atof(av[arg+3]);
+        c3 = c_add(c1, c2);
+        printf("(%f + %fi) + (%f + %fi) = (%f + %fi)\n",
+               c1.real, c1.imag,
+               c2.real, c2.imag,
+               c3.real, c3.imag);
+    }
+}
+#endif