FA-69311 / Tide and marine navigation tables / Open access

Deviation card interpolation: Interpolation assumes a 45 degree card spacing · case 01

Irregular cards give deviations outside the neighbouring values.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The interpolation weight divides by a fixed 45 degrees.

VERIFIED REPAIR

Divide by the actual gap h1-h0.

Unsuccessful approach: Using the first card gap for every segment breaks irregular cards.

Case contract

Input [heading, card]: card lists [compass heading, deviation] pairs (east positive) in any order. Headings wrap modulo 360; deviation is linearly interpolated between neighbouring card headings, including across the 360/0 seam. Return deviation rounded to 2 decimals.

Why this case matters

Tide tables and passage plans turn published predictions into go/no-go decisions about depth, clearance and timing.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    hdg,card=x
    pts=sorted(card)
    first=pts[0][0]
    t=hdg%360
    if t<first: t+=360
    pts.append([first+360,pts[0][1]])
    for k in range(len(pts)-1):
        h0,d0=pts[k]; h1,d1=pts[k+1]
        if h0<=t<h1:
            return round(d0+(d1-d0)*(t-h0)/45,2)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('deviation card interpolation [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.83), ('deviation card interpolation [0, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [0, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.0), ('deviation card interpolation [20, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [20, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.67), ('deviation card interpolation [90, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [90, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.0), ('deviation card interpolation [100, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [100, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 0.44), ('deviation card interpolation [200, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [200, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], -2.56), ('deviation card interpolation [330, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [330, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.67)], [('deviation card interpolation [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 1.88), ('deviation card interpolation [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.94), ('deviation card interpolation [100, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [100, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 0.44), ('deviation card interpolation [200, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [200, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], -2.56), ('deviation card interpolation [330, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [330, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.67), ('deviation card interpolation [359, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [359, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.99), ('deviation card interpolation [360, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [360, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.0)], [('deviation card interpolation [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.94), ('deviation card interpolation [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.25), ('deviation card interpolation [359, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [359, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.99), ('deviation card interpolation [360, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [360, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.0), ('deviation card interpolation [-30, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [-30, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.67), ('deviation card interpolation [725, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [725, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.17), ('deviation card interpolation [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.83)], [('deviation card interpolation [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.25), ('deviation card interpolation [350, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [350, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.58), ('deviation card interpolation [725, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [725, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.17), ('deviation card interpolation [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.83), ('deviation card interpolation [15, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [15, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 1.0), ('deviation card interpolation [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 1.88), ('deviation card interpolation [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.94)], [('deviation card interpolation [350, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [350, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.58), ('deviation card interpolation [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.83), ('deviation card interpolation [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 1.88), ('deviation card interpolation [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.94), ('deviation card interpolation [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.25), ('deviation card interpolation [60, [[315, 1.5], [270, 0.5], [225, -2.0], [180, -3.0], [135, -1.5], [90, 1.0], [45, 3.5], [0, 2.0]]]', [60, [[315, 1.5], [270, 0.5], [225, -2.0], [180, -3.0], [135, -1.5], [90, 1.0], [45, 3.5], [0, 2.0]]], 2.67), ('deviation card interpolation [250, [[315, 1.5], [270, 0.5], [225, -2.0], [180, -3.0], [135, -1.5], [90, 1.0], [45, 3.5], [0, 2.0]]]', [250, [[315, 1.5], [270, 0.5], [225, -2.0], [180, -3.0], [135, -1.5], [90, 1.0], [45, 3.5], [0, 2.0]]], -0.61)]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
deviation card interpolation [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]	`2.17`	`0.83`	Failed
deviation card interpolation [0, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`2.0`	`2.0`	Passed
deviation card interpolation [20, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`2.67`	`2.67`	Passed
deviation card interpolation [90, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`1.0`	`1.0`	Passed
deviation card interpolation [100, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`0.44`	`0.44`	Passed
deviation card interpolation [200, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`-2.56`	`-2.56`	Passed
deviation card interpolation [330, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`1.67`	`1.67`	Passed

SHA-256 / bd7154bbe89c6030baa58ebd045bb275580b2fd8b0c98114d1adccde25bd4672

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    hdg,card=x
    pts=sorted(card)
    first=pts[0][0]
    t=hdg%360
    if t<first: t+=360
    pts.append([first+360,pts[0][1]])
    for k in range(len(pts)-1):
        h0,d0=pts[k]; h1,d1=pts[k+1]
        if h0<=t<h1:
            return round(d0+(d1-d0)*(t-h0)/(pts[1][0]-pts[0][0]),2)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('deviation card interpolation [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.83), ('deviation card interpolation [0, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [0, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.0), ('deviation card interpolation [20, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [20, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.67), ('deviation card interpolation [90, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [90, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.0), ('deviation card interpolation [100, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [100, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 0.44), ('deviation card interpolation [200, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [200, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], -2.56), ('deviation card interpolation [330, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [330, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.67)], [('deviation card interpolation [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 1.88), ('deviation card interpolation [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.94), ('deviation card interpolation [100, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [100, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 0.44), ('deviation card interpolation [200, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [200, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], -2.56), ('deviation card interpolation [330, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [330, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.67), ('deviation card interpolation [359, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [359, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.99), ('deviation card interpolation [360, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [360, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.0)], [('deviation card interpolation [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.94), ('deviation card interpolation [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.25), ('deviation card interpolation [359, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [359, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.99), ('deviation card interpolation [360, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [360, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.0), ('deviation card interpolation [-30, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [-30, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.67), ('deviation card interpolation [725, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [725, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.17), ('deviation card interpolation [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.83)], [('deviation card interpolation [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.25), ('deviation card interpolation [350, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [350, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.58), ('deviation card interpolation [725, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [725, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.17), ('deviation card interpolation [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.83), ('deviation card interpolation [15, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [15, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 1.0), ('deviation card interpolation [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 1.88), ('deviation card interpolation [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.94)], [('deviation card interpolation [350, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [350, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.58), ('deviation card interpolation [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.83), ('deviation card interpolation [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 1.88), ('deviation card interpolation [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.94), ('deviation card interpolation [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.25), ('deviation card interpolation [60, [[315, 1.5], [270, 0.5], [225, -2.0], [180, -3.0], [135, -1.5], [90, 1.0], [45, 3.5], [0, 2.0]]]', [60, [[315, 1.5], [270, 0.5], [225, -2.0], [180, -3.0], [135, -1.5], [90, 1.0], [45, 3.5], [0, 2.0]]], 2.67), ('deviation card interpolation [250, [[315, 1.5], [270, 0.5], [225, -2.0], [180, -3.0], [135, -1.5], [90, 1.0], [45, 3.5], [0, 2.0]]]', [250, [[315, 1.5], [270, 0.5], [225, -2.0], [180, -3.0], [135, -1.5], [90, 1.0], [45, 3.5], [0, 2.0]]], -0.61)]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
deviation card interpolation [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]	`1.5`	`0.83`	Failed
deviation card interpolation [0, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`2.0`	`2.0`	Passed
deviation card interpolation [20, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`2.67`	`2.67`	Passed
deviation card interpolation [90, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`1.0`	`1.0`	Passed
deviation card interpolation [100, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`0.44`	`0.44`	Passed
deviation card interpolation [200, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`-2.56`	`-2.56`	Passed
deviation card interpolation [330, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`1.67`	`1.67`	Passed

SHA-256 / bf1ffbacf5dc43b5fc86293feb330dbf0876b5d343e275733f0805a3c0b6736e

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    hdg,card=x
    pts=sorted(card)
    first=pts[0][0]
    t=hdg%360
    if t<first: t+=360
    pts.append([first+360,pts[0][1]])
    for k in range(len(pts)-1):
        h0,d0=pts[k]; h1,d1=pts[k+1]
        if h0<=t<h1:
            return round(d0+(d1-d0)*(t-h0)/(h1-h0),2)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('deviation card interpolation [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.83), ('deviation card interpolation [0, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [0, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.0), ('deviation card interpolation [20, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [20, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.67), ('deviation card interpolation [90, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [90, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.0), ('deviation card interpolation [100, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [100, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 0.44), ('deviation card interpolation [200, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [200, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], -2.56), ('deviation card interpolation [330, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [330, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.67)], [('deviation card interpolation [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 1.88), ('deviation card interpolation [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.94), ('deviation card interpolation [100, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [100, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 0.44), ('deviation card interpolation [200, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [200, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], -2.56), ('deviation card interpolation [330, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [330, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.67), ('deviation card interpolation [359, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [359, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.99), ('deviation card interpolation [360, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [360, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.0)], [('deviation card interpolation [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.94), ('deviation card interpolation [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.25), ('deviation card interpolation [359, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [359, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.99), ('deviation card interpolation [360, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [360, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.0), ('deviation card interpolation [-30, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [-30, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 1.67), ('deviation card interpolation [725, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [725, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.17), ('deviation card interpolation [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.83)], [('deviation card interpolation [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.25), ('deviation card interpolation [350, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [350, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.58), ('deviation card interpolation [725, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]', [725, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]], 2.17), ('deviation card interpolation [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.83), ('deviation card interpolation [15, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [15, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 1.0), ('deviation card interpolation [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 1.88), ('deviation card interpolation [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.94)], [('deviation card interpolation [350, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [350, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.58), ('deviation card interpolation [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 0.83), ('deviation card interpolation [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [50, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], 1.88), ('deviation card interpolation [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [150, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.94), ('deviation card interpolation [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]', [300, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]], -0.25), ('deviation card interpolation [60, [[315, 1.5], [270, 0.5], [225, -2.0], [180, -3.0], [135, -1.5], [90, 1.0], [45, 3.5], [0, 2.0]]]', [60, [[315, 1.5], [270, 0.5], [225, -2.0], [180, -3.0], [135, -1.5], [90, 1.0], [45, 3.5], [0, 2.0]]], 2.67), ('deviation card interpolation [250, [[315, 1.5], [270, 0.5], [225, -2.0], [180, -3.0], [135, -1.5], [90, 1.0], [45, 3.5], [0, 2.0]]]', [250, [[315, 1.5], [270, 0.5], [225, -2.0], [180, -3.0], [135, -1.5], [90, 1.0], [45, 3.5], [0, 2.0]]], -0.61)]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
deviation card interpolation [5, [[15, 1.0], [75, 2.5], [120, 0.0], [200, -2.5], [285, -0.5]]]	`0.83`	`0.83`	Passed
deviation card interpolation [0, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`2.0`	`2.0`	Passed
deviation card interpolation [20, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`2.67`	`2.67`	Passed
deviation card interpolation [90, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`1.0`	`1.0`	Passed
deviation card interpolation [100, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`0.44`	`0.44`	Passed
deviation card interpolation [200, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`-2.56`	`-2.56`	Passed
deviation card interpolation [330, [[0, 2.0], [45, 3.5], [90, 1.0], [135, -1.5], [180, -3.0], [225, -2.0], [270, 0.5], [315, 1.5]]]	`1.67`	`1.67`	Passed

SHA-256 / e446b1b530b8a520d3e166bfab94f6f0a81d86dde7c266d915cdb8f2ce02174e

Verification & scope

A deterministic toy model with stipulated rules and constants; not certified hydrographic software or a substitute for official tide tables. 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.

Observations recorded using Python 3.12.14 at 2026-09-29T14:48:10.230677+00:00.

Case digest / 1e27c0731605f665aba1f928aa50a1562a89c1bc23f8234cbca6235bffc3ecb8