From b73a1146a1af2eabe6af1ba043fc6ff5ef8731ab Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Wed, 2 Apr 2025 14:55:48 -0700
Subject: parse negative floats

---
 chapter21/src/main/java/com/seaofnodes/simple/Parser.java           | 1 +
 chapter21/src/test/java/com/seaofnodes/simple/progs/newtonFloat.smp | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

(limited to 'chapter21/src')

diff --git a/chapter21/src/main/java/com/seaofnodes/simple/Parser.java b/chapter21/src/main/java/com/seaofnodes/simple/Parser.java
index 092c5a9e..e1120a2f 100644
--- a/chapter21/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter21/src/main/java/com/seaofnodes/simple/Parser.java
@@ -1670,6 +1670,7 @@ public class Parser {
             while( Character.isDigit(c=nextChar()) ) ;
             if( !(c=='e' || c=='.') )
                 return --_position - old;
+            if( peek() == '-' ) nextChar();
             while( Character.isDigit(c=nextChar()) || c=='e' || c=='.' ) ;
             return -(--_position - old);
         }
diff --git a/chapter21/src/test/java/com/seaofnodes/simple/progs/newtonFloat.smp b/chapter21/src/test/java/com/seaofnodes/simple/progs/newtonFloat.smp
index 5cb798a9..b41fc26e 100644
--- a/chapter21/src/test/java/com/seaofnodes/simple/progs/newtonFloat.smp
+++ b/chapter21/src/test/java/com/seaofnodes/simple/progs/newtonFloat.smp
@@ -1,10 +1,11 @@
 // -*- mode: java;  -*-
 // Newtons approximation to the square root
 val sqrt = { flt x ->
+    flt epsilon = 1e-57;
     flt guess = x;
     while( 1 ) {
         flt next = (x/guess + guess)/2;
-        if( next == guess ) return guess;
+        if( guess-epsilon <= next & next <= guess+epsilon ) return guess;
         guess = next;
     }
 };
-- 
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