From cc099d8fc60a7693417754f9b3a3f51f0952f9a3 Mon Sep 17 00:00:00 2001
From: Robert Muir <rmuir@apache.org>
Date: Mon, 18 Apr 2016 09:15:04 -0400
Subject: [PATCH] LUCENE-7185: handle underflow

---
 .../src/java/org/apache/lucene/geo/GeoTestUtil.java           | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lucene/test-framework/src/java/org/apache/lucene/geo/GeoTestUtil.java b/lucene/test-framework/src/java/org/apache/lucene/geo/GeoTestUtil.java
index eb48a8fd89d..98e296684ac 100644
--- a/lucene/test-framework/src/java/org/apache/lucene/geo/GeoTestUtil.java
+++ b/lucene/test-framework/src/java/org/apache/lucene/geo/GeoTestUtil.java
@@ -195,6 +195,10 @@ public class GeoTestUtil {
     } else {
       double x = nextLongitudeBetween(minX, maxX);
       double y = (y1 - y2) / (x1 - x2) * (x-x1) + y1;
+      if (Double.isFinite(y) == false) {
+        // this can happen due to underflow when delta between x values is wonderfully tiny!
+        y = Math.copySign(90, x1);
+      }
       double delta = (maxY - minY) * 0.01;
       // our formula may put the targeted Y out of bounds
       y = Math.min(90, y);