1 files changed, 52 insertions, 0 deletions
diff --git a/lib/lgamma.c b/lib/lgamma.c
new file mode 100644
index 0000000..02ac593
--- /dev/null
+++ b/lib/lgamma.c
@@ -0,0 +1,52 @@
+// Lgamma
+//
+// lgamma
+//
+// Natural log of gamma function
+//
+// ln(|Γ(x)|)
+//
+// Inputs:    1
+// Outputs:   1
+// Constants: 0
+
+
+#include <math.h>
+#include "ts.h"
+
+
+ts_parameter_t const ts_lgamma_p = { .n_inputs = 1, .n_outputs = 1, .n_constants = 0, .params_size = 0 };
+
+uint_t ts_lgamma_offset( ts_constant_t const *c )
+{
+	( void )c;
+	return ( 0 );
+}
+
+int ts_lgamma(
+	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_lgamma_p );
+	(void)c;
+	for( uint_t i = 0; i < n; ++i )
+	{
+		fp_t xv = x[0][i];
+		if( xv <= 0.0 )
+		{
+			fp_t intpart;
+			if (modf(xv, &intpart) != 0.0)
+				y[0][i] = lgamma(xv);
+			else
+				y[0][i] = NAN;
+		}
+		else
+			y[0][i] = lgamma( xv );
+	}
+	return 0;
+}
+
+
+