diff --git a/math/complex_add.c b/math/complex_add.c
new file mode 100644
index 0000000000..f0d56774a8
--- /dev/null
+++ b/math/complex_add.c
@@ -0,0 +1,75 @@
+/**
+ * @file
+ * @brief Function to add up two complex numbers.
+ */
+#define _USE_MATH_DEFINES /**< required for MS Visual C */
+#include <assert.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+/**
+ * @brief Function to add two complex numbers.
+ *\f{eqnarray*}{
+ x + yi &=& (x_1 + y_1i) + (x_2 + y_2i)
+ x &=& x_1 + x_2
+ y &=& y_1 + y_2
+ \f}
+ * @param [in] x1 real part of the first summand
+ * @param [in] y1 imaginary part of the first summand
+ * @param [in] x2 real part of the second summand
+ * @param [in] y2 imaginary part of the second summand
+ * @param [out] x pointer to real part of the sum
+ * @param [out] y pointer to imaginary part of the sum
+ */
+void summing(double x1, double y1, double x2, double y2, double *x, double *y)
+{
+    *x = x1 + x2;
+    *y = y1 + y2;
+}
+
+/**
+ * @brief Generate a random number in the given limits
+ *
+ * @param lim1 lower limit
+ * @param lim2 upper limit
+ * @return random number in the given range
+ */
+double get_rand(double lim1, double lim2)
+{
+    double r = (double)rand() / RAND_MAX;  // value in [0,1)
+    return (lim2 - lim1) * r + lim1;       // scale to range
+}
+
+/**
+ * @brief Test implementation
+ *
+ */
+void test()
+{
+    srand(10);
+    int NUM_TESTS = 5;
+
+    for (int i = 0; i < NUM_TESTS; i++)
+    {
+        double x, y;
+        printf("Test %d.... ", i);
+        double x1 = get_rand(-5, 5);
+        double y1 = get_rand(-5, 5);
+        double x2 = get_rand(-5, 5);
+        double y2 = get_rand(-5, 5);
+        printf("(%.2g + %.2g i) + (%.2g + %.2g i)", x1, y1, x2, y2);
+        summing(x1, y1, x2, y2, &x, &y);
+        assert(fabs(x - (x1 + x2)) < 0.01);
+        assert(fabs(y - (y1 + y2)) < 0.01);
+        printf("passed\n");
+    }
+}
+
+/** Main function */
+int main()
+{
+    test();
+
+    return 0;
+}