{"abstract":"In the morning the tracker is commanded past its east mechanical stop.","category":"Solar tracker geometry","checks":7,"contract":"Sun azimuth clockwise from north and elevation in degrees. The horizontal axis points to axis_az; rotation is positive toward azimuth axis_az+90. Sun vector east=cos(el)sin(az), north=cos(el)cos(az), up=sin(el). Rotation = atan2(component along axis_az+90, up). Clamp to +-max_angle (status 'limited', else 'tracking'); sun_el <= 0 returns [0.0, 'night']. Round to 3 decimals.","contract_signature":"sun_az, sun_el, axis_az, max_angle","evaluation_group":"w2-solar_tracker_geometry-horizontal-axis-true-tracking","failed_approach":"Clamping to +max_angle alone sends morning limits to the west stop.","family":"w2-solar_tracker_geometry-horizontal-axis-true-tracking-symmetric-rotation-limit","id":"FA-93361","implementations":{"attempt":{"sha256":"b76fc8c4298c4e2e6419f73745754336eb6ede858c677c4b86d3e73b5a0c2a6c","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(sun_az, sun_el, axis_az, max_angle):\n    if sun_el <= 0:\n        return [0.0, 'night']\n    az = math.radians(sun_az)\n    el = math.radians(sun_el)\n    e = math.cos(el) * math.sin(az)\n    n = math.cos(el) * math.cos(az)\n    u = math.sin(el)\n    pa = math.radians(axis_az + 90)\n    perp = e * math.sin(pa) + n * math.cos(pa)\n    rot = math.degrees(math.atan2(perp, u))\n    status = 'tracking'\n    if abs(rot) > max_angle:\n        rot = max_angle\n        status = 'limited'\n    return [round(rot, 3), status]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['boundary: sun on the horizon', [90, 0, 180, 60], [0.0, 'night']],\n  ['normal: solar noon on N-S axis', [180, 60, 180, 60], [0.0, 'tracking']],\n  ['boundary: low morning sun hits east limit', [90, 10, 180, 60], [-60.0, 'limited']],\n  ['regression: symmetric rotation limit', [30, 10, 180, 55], [-55.0, 'limited']],\n  ['regression: symmetric rotation limit (partial repair)', [250, 10, 0, 45], [-45.0, 'limited']],\n  ['control 1', [150, 10, 190, 45], [-45.0, 'limited']],\n  ['control 2', [180, 89, 0, 55], [0.0, 'tracking']]],\n [['boundary: sun on the horizon', [90, 0, 180, 60], [0.0, 'night']],\n  ['normal: solar noon on N-S axis', [180, 60, 180, 60], [0.0, 'tracking']],\n  ['boundary: low morning sun hits east limit', [90, 10, 180, 60], [-60.0, 'limited']],\n  ['regression: symmetric rotation limit', [150, 10, 170, 60], [-60.0, 'limited']],\n  ['regression: symmetric rotation limit (partial repair)', [100, 20, 170, 60], [-60.0, 'limited']],\n  ['control 1', [60, 0, 20, 45], [0.0, 'night']],\n  ['control 2', [340, 60, 170, 45], [5.725, 'tracking']]],\n [['boundary: sun on the horizon', [90, 0, 180, 60], [0.0, 'night']],\n  ['normal: solar noon on N-S axis', [180, 60, 180, 60], [0.0, 'tracking']],\n  ['boundary: low morning sun hits east limit', [90, 10, 180, 60], [-60.0, 'limited']],\n  ['regression: symmetric rotation limit', [100, 20, 180, 45], [-45.0, 'limited']],\n  ['regression: symmetric rotation limit (partial repair)', [100, 45, 190, 45], [-45.0, 'limited']],\n  ['control 1', [135, 0, 0, 60], [0.0, 'night']],\n  ['control 2', [60, 20, 170, 55], [-55.0, 'limited']]],\n [['boundary: sun on the horizon', [90, 0, 180, 60], [0.0, 'night']],\n  ['normal: solar noon on N-S axis', [180, 60, 180, 60], [0.0, 'tracking']],\n  ['boundary: low morning sun hits east limit', [90, 10, 180, 60], [-60.0, 'limited']],\n  ['regression: symmetric rotation limit', [90, 3, 180, 60], [-60.0, 'limited']],\n  ['regression: symmetric rotation limit (partial repair)', [100, 3, 190, 60], [-60.0, 'limited']],\n  ['control 1', [90, 20, 0, 60], [60.0, 'limited']],\n  ['control 2', [30, 3, 190, 45], [-45.0, 'limited']]],\n [['boundary: sun on the horizon', [90, 0, 180, 60], [0.0, 'night']],\n  ['normal: solar noon on N-S axis', [180, 60, 180, 60], [0.0, 'tracking']],\n  ['boundary: low morning sun hits east limit', [90, 10, 180, 60], [-60.0, 'limited']],\n  ['regression: symmetric rotation limit', [30, 20, 170, 45], [-45.0, 'limited']],\n  ['regression: symmetric rotation limit (partial repair)', [340, 3, 20, 55], [-55.0, 'limited']],\n  ['control 1', [100, 3, 190, 60], [-60.0, 'limited']],\n  ['control 2', [90, 75, 170, 55], [-14.782, 'tracking']]]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"a2522390c219d2a7bd69178cdd1111a70d2326f1bc5d709e1503eeb6b377bd37","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(sun_az, sun_el, axis_az, max_angle):\n    if sun_el <= 0:\n        return [0.0, 'night']\n    az = math.radians(sun_az)\n    el = math.radians(sun_el)\n    e = math.cos(el) * math.sin(az)\n    n = math.cos(el) * math.cos(az)\n    u = math.sin(el)\n    pa = math.radians(axis_az + 90)\n    perp = e * math.sin(pa) + n * math.cos(pa)\n    rot = math.degrees(math.atan2(perp, u))\n    status = 'tracking'\n    if rot > max_angle:\n        rot = math.copysign(max_angle, rot)\n        status = 'limited'\n    return [round(rot, 3), status]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['boundary: sun on the horizon', [90, 0, 180, 60], [0.0, 'night']],\n  ['normal: solar noon on N-S axis', [180, 60, 180, 60], [0.0, 'tracking']],\n  ['boundary: low morning sun hits east limit', [90, 10, 180, 60], [-60.0, 'limited']],\n  ['regression: symmetric rotation limit', [30, 10, 180, 55], [-55.0, 'limited']],\n  ['regression: symmetric rotation limit (partial repair)', [250, 10, 0, 45], [-45.0, 'limited']],\n  ['control 1', [150, 10, 190, 45], [-45.0, 'limited']],\n  ['control 2', [180, 89, 0, 55], [0.0, 'tracking']]],\n [['boundary: sun on the horizon', [90, 0, 180, 60], [0.0, 'night']],\n  ['normal: solar noon on N-S axis', [180, 60, 180, 60], [0.0, 'tracking']],\n  ['boundary: low morning sun hits east limit', [90, 10, 180, 60], [-60.0, 'limited']],\n  ['regression: symmetric rotation limit', [150, 10, 170, 60], [-60.0, 'limited']],\n  ['regression: symmetric rotation limit (partial repair)', [100, 20, 170, 60], [-60.0, 'limited']],\n  ['control 1', [60, 0, 20, 45], [0.0, 'night']],\n  ['control 2', [340, 60, 170, 45], [5.725, 'tracking']]],\n [['boundary: sun on the horizon', [90, 0, 180, 60], [0.0, 'night']],\n  ['normal: solar noon on N-S axis', [180, 60, 180, 60], [0.0, 'tracking']],\n  ['boundary: low morning sun hits east limit', [90, 10, 180, 60], [-60.0, 'limited']],\n  ['regression: symmetric rotation limit', [100, 20, 180, 45], [-45.0, 'limited']],\n  ['regression: symmetric rotation limit (partial repair)', [100, 45, 190, 45], [-45.0, 'limited']],\n  ['control 1', [135, 0, 0, 60], [0.0, 'night']],\n  ['control 2', [60, 20, 170, 55], [-55.0, 'limited']]],\n [['boundary: sun on the horizon', [90, 0, 180, 60], [0.0, 'night']],\n  ['normal: solar noon on N-S axis', [180, 60, 180, 60], [0.0, 'tracking']],\n  ['boundary: low morning sun hits east limit', [90, 10, 180, 60], [-60.0, 'limited']],\n  ['regression: symmetric rotation limit', [90, 3, 180, 60], [-60.0, 'limited']],\n  ['regression: symmetric rotation limit (partial repair)', [100, 3, 190, 60], [-60.0, 'limited']],\n  ['control 1', [90, 20, 0, 60], [60.0, 'limited']],\n  ['control 2', [30, 3, 190, 45], [-45.0, 'limited']]],\n [['boundary: sun on the horizon', [90, 0, 180, 60], [0.0, 'night']],\n  ['normal: solar noon on N-S axis', [180, 60, 180, 60], [0.0, 'tracking']],\n  ['boundary: low morning sun hits east limit', [90, 10, 180, 60], [-60.0, 'limited']],\n  ['regression: symmetric rotation limit', [30, 20, 170, 45], [-45.0, 'limited']],\n  ['regression: symmetric rotation limit (partial repair)', [340, 3, 20, 55], [-55.0, 'limited']],\n  ['control 1', [100, 3, 190, 60], [-60.0, 'limited']],\n  ['control 2', [90, 75, 170, 55], [-14.782, 'tracking']]]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"Deterministic stipulated toy contract for teaching; no claim of conformance with any standard, vendor protocol or production controller. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"w2-solar_tracker_geometry-horizontal-axis-true-tracking-symmetric-rotation-limit","generated_at":"2026-09-29T14:51:54.391464+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Single-axis and dual-axis solar trackers turn a sun direction into actuator commands; a sign, frame or limit mistake points a whole plant away from the sun or into a mechanical stop.","root_cause":"Only the positive rotation limit is enforced.","sha256":"3e27a144905fd6be707b4627a29dcf14b510cc1959192f1458b1957fc68d618f","title":"Horizontal single-axis true tracking: symmetric rotation limit · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":40.089,"exit_code":1,"observations":[{"actual":[0.0,"night"],"check":"boundary: sun on the horizon","expected":[0.0,"night"],"passed":true},{"actual":[0.0,"tracking"],"check":"normal: solar noon on N-S axis","expected":[0.0,"tracking"],"passed":true},{"actual":[60,"limited"],"check":"boundary: low morning sun hits east limit","expected":[-60.0,"limited"],"passed":false},{"actual":[55,"limited"],"check":"regression: symmetric rotation limit","expected":[-55.0,"limited"],"passed":false},{"actual":[45,"limited"],"check":"regression: symmetric rotation limit (partial repair)","expected":[-45.0,"limited"],"passed":false},{"actual":[45,"limited"],"check":"control 1","expected":[-45.0,"limited"],"passed":false},{"actual":[0.0,"tracking"],"check":"control 2","expected":[0.0,"tracking"],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary: sun on the horizon\", \"actual\": [0.0, \"night\"], \"expected\": [0.0, \"night\"], \"passed\": true}, {\"check\": \"normal: solar noon on N-S axis\", \"actual\": [0.0, \"tracking\"], \"expected\": [0.0, \"tracking\"], \"passed\": true}, {\"check\": \"boundary: low morning sun hits east limit\", \"actual\": [60, \"limited\"], \"expected\": [-60.0, \"limited\"], \"passed\": false}, {\"check\": \"regression: symmetric rotation limit\", \"actual\": [55, \"limited\"], \"expected\": [-55.0, \"limited\"], \"passed\": false}, {\"check\": \"regression: symmetric rotation limit (partial repair)\", \"actual\": [45, \"limited\"], \"expected\": [-45.0, \"limited\"], \"passed\": false}, {\"check\": \"control 1\", \"actual\": [45, \"limited\"], \"expected\": [-45.0, \"limited\"], \"passed\": false}, {\"check\": \"control 2\", \"actual\": [0.0, \"tracking\"], \"expected\": [0.0, \"tracking\"], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.387,"exit_code":1,"observations":[{"actual":[0.0,"night"],"check":"boundary: sun on the horizon","expected":[0.0,"night"],"passed":true},{"actual":[0.0,"tracking"],"check":"normal: solar noon on N-S axis","expected":[0.0,"tracking"],"passed":true},{"actual":[-80.0,"tracking"],"check":"boundary: low morning sun hits east limit","expected":[-60.0,"limited"],"passed":false},{"actual":[-70.575,"tracking"],"check":"regression: symmetric rotation limit","expected":[-55.0,"limited"],"passed":false},{"actual":[-79.372,"tracking"],"check":"regression: symmetric rotation limit (partial repair)","expected":[-45.0,"limited"],"passed":false},{"actual":[-74.66,"tracking"],"check":"control 1","expected":[-45.0,"limited"],"passed":false},{"actual":[0.0,"tracking"],"check":"control 2","expected":[0.0,"tracking"],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary: sun on the horizon\", \"actual\": [0.0, \"night\"], \"expected\": [0.0, \"night\"], \"passed\": true}, {\"check\": \"normal: solar noon on N-S axis\", \"actual\": [0.0, \"tracking\"], \"expected\": [0.0, \"tracking\"], \"passed\": true}, {\"check\": \"boundary: low morning sun hits east limit\", \"actual\": [-80.0, \"tracking\"], \"expected\": [-60.0, \"limited\"], \"passed\": false}, {\"check\": \"regression: symmetric rotation limit\", \"actual\": [-70.575, \"tracking\"], \"expected\": [-55.0, \"limited\"], \"passed\": false}, {\"check\": \"regression: symmetric rotation limit (partial repair)\", \"actual\": [-79.372, \"tracking\"], \"expected\": [-45.0, \"limited\"], \"passed\": false}, {\"check\": \"control 1\", \"actual\": [-74.66, \"tracking\"], \"expected\": [-45.0, \"limited\"], \"passed\": false}, {\"check\": \"control 2\", \"actual\": [0.0, \"tracking\"], \"expected\": [0.0, \"tracking\"], \"passed\": true}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}