1 files changed, 50 insertions, 0 deletions
diff --git a/test/gourdinl/c/random.c b/test/gourdinl/c/random.c
new file mode 100644
index 00000000..50aa5737
--- /dev/null
+++ b/test/gourdinl/c/random.c
@@ -0,0 +1,50 @@
+/* Generating random number sequences using the formula (linear congruence)
+	x[k+1] = (a*x[k] + c)mod m
+   where a, c, and m are parameters set by the user and passed as command line 
+   parameters together with a seed i.e. x[0]
+   As a simple example try  a=7, c=1, m=13, and seed=5
+   A more sophisticated selection would be a=69069, c=0, 
+   m=2^32=4294967296, and seed=31
+   It will print out, in a sort of random order, up to m-1 distinct values. 
+   Then it loops.
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+static long seed = 13;
+static long a;
+static long c;
+static long m;
+
+void random_init(long s) {
+    if (s != 0) seed = s;
+}
+
+long random() {
+	seed = (a*seed + c)%m;
+	return seed;
+    }
+
+int main(int argc, char * argv[]) {
+    if (argc != 5) {
+	printf("usage: %s a, c, m, seed\n", argv[0]);
+	return 1;
+    }
+    a = atoi(argv[1]);
+    c = atoi(argv[2]);
+    m = atoi(argv[3]);
+    long s = atoi(argv[4]);
+    random_init(s);
+    int k;
+    for (k = 0; k < m-1; k++) { 
+	printf("%8ld", random());
+	if (k % 8 == 7) { // after 8 elements go to a new line
+	    printf("\n");
+	    sleep(1); // sleep for a second
+	} 
+    }
+    printf("\n");
+    return 0;
+}