1 files changed, 58 insertions, 0 deletions
diff --git a/lib/binomial.c b/lib/binomial.c
new file mode 100644
index 0000000..9b50698
--- /dev/null
+++ b/lib/binomial.c
@@ -0,0 +1,58 @@
+// Binomial Coefficient
+//
+// binomial - C(n, k)
+//
+// Number of combinations: C(n, k) = n! / (k! * (n-k)!)
+//
+// Inputs:    2 (n, k)
+// Outputs:   1 (coefficient)
+// Constants: 0
+
+#include <math.h>
+#include "ts.h"
+
+
+ts_parameter_t const ts_binomial_p = { .n_inputs = 2, .n_outputs = 1, .n_constants = 0, .params_size = 0 };
+
+uint_t ts_binomial_offset( ts_constant_t const *c )
+{
+	( void )c;
+	return ( 0 );
+}
+
+int ts_binomial(
+	fp_t * const *y, uint_t y_n,
+	fp_t const * const *x, uint_t x_n,
+	uint_t n, ts_constant_t const *c
+)
+{
+	TS_PROLOGUE( ts_binomial_p );
+	(void)c;
+    /* C(n, k) = n! / (k! * (n-k)!) */
+    for (uint_t i = 0; i < n; ++i)
+    {
+        fp_t n_val = floor(x[0][i]);
+        fp_t k_val = floor(x[1][i]);
+
+        if (k_val > n_val || k_val < 0 || n_val < 0)
+        {
+            y[0][i] = 0;
+            continue;
+        }
+
+        /* Use symmetry: C(n,k) = C(n, n-k) */
+        if (k_val > n_val - k_val)
+            k_val = n_val - k_val;
+
+        fp_t result = 1;
+        for (uint_t j = 0; j < (uint_t)k_val; ++j)
+        {
+            result = result * (n_val - j) / (j + 1);
+        }
+        y[0][i] = result;
+    }
+	return 0;
+}
+
+
+