From 07e18043145f3d91c8ea7ec3ad41b3c905585277 Mon Sep 17 00:00:00 2001
From: Ethan Werner <mail@ethanwerner.com>
Date: Wed, 1 Jul 2026 09:42:39 +0400
Subject: initial commit: ts time series analysis library v0.1.0

- 354 financial and mathematical time-series indicators
- Uniform C11 API with consistent function signatures
- 349 passing tests with -Werror
- Static and shared library builds
- pkg-config integration
- Python bindings
- Fuzzing and sanitizer support
- Security hardening flags
---
 lib/starc_lower.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 lib/starc_lower.c

(limited to 'lib/starc_lower.c')

diff --git a/lib/starc_lower.c b/lib/starc_lower.c
new file mode 100644
index 0000000..97ac02f
--- /dev/null
+++ b/lib/starc_lower.c
@@ -0,0 +1,74 @@
+// Starc Lower
+//
+// starc_lower
+//
+// STARC Lower Band
+//
+// 
+//
+// Inputs:    4
+// Outputs:   1
+// Constants: 2
+
+
+#include <math.h>
+#include "ts.h"
+
+typedef struct {
+    uint_t k;
+    fp_t mult;
+} ts_starc_lower_params_t;
+
+ts_parameter_t const ts_starc_lower_p = { .n_inputs = 4, .n_outputs = 1, .n_constants = 2, .params_size = sizeof(ts_starc_lower_params_t) };
+
+uint_t ts_starc_lower_offset( ts_constant_t const *c )
+{
+	( void )c;
+	return ( c ? ((ts_starc_lower_params_t *)c)->k > 0 ? ((ts_starc_lower_params_t *)c)->k - 1 : 0 : 0 );
+}
+
+int ts_starc_lower(
+	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_starc_lower_p );
+	if ( !c ) return -1;
+	uint_t k = ((ts_starc_lower_params_t *)c)->k;
+	if( k == 0 ) return -1;
+	fp_t mult = ((ts_starc_lower_params_t *)c)->mult;
+
+ uint_t half_k = k / 2;
+    if (n <= half_k) return -1;
+
+	uint_t last = k - 1;
+	for( uint_t i = k - 1; i < n - half_k; ++i )
+	{
+		fp_t middle_sum = 0;
+		fp_t atr_sum = 0;
+
+		for( uint_t j = 0; j < k; ++j )
+		{
+			uint_t idx = i - half_k + j;
+			middle_sum += ts_c( x, idx );
+
+			fp_t tr = ts_h( x, idx ) - ts_l( x, idx );
+			if( idx > 0 )
+			{
+				fp_t h_pc = fabs( ts_h( x, idx ) - ts_c( x, idx - 1 ) );
+				fp_t l_pc = fabs( ts_l( x, idx ) - ts_c( x, idx - 1 ) );
+				if( h_pc > tr ) tr = h_pc;
+				if( l_pc > tr ) tr = l_pc;
+			}
+			atr_sum += tr;
+		}
+
+		y[0][i] = middle_sum / k - mult * atr_sum / k;
+		last = i;
+	}
+	for( uint_t i = last + 1; i < n; ++i )
+		y[0][i] = y[0][last];
+	return 0;
+}
+
-- 
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