Merge pull request #3870 from panzone/correct-real-write

Correct real write bug

[Patch prepared by @Panzone and reviewed/merged by @mppf]

This pull request tries to correct the bug noticed in #2148. It will switch to an exponential notation if the standard precision isn't enough to print the decimal part of the number.

Passed test/io and test/release on both linux64 and darwin with default settings.
[And passed full local testing]

runtime/src/qio/qio_formatted.c

@@ -2589,6 +2589,28 @@ int _ltoa(char* restrict dst, size_t size, uint64_t num, int isnegative,
   return i;
 }
 
+//This function finds where the last non-zero digit
+//is in the decimal part of an exponential number.
+//
+//This will be used in _ftoa_core for resolve a
+//a problem about trailing zeroes.
+static int _find_prec(char *buf, int len){
+  int dp_index = 0;
+  int last_dig = 0;
+  int index = 0;
+
+  //Find where the decimal point is
+  while( dp_index < len && buf[dp_index++] != '.');
+
+  //Explore the decimal part for find where the
+  //last non-zero digit is.
+  for( index = dp_index; index < len && buf[index] != 'e'; index++ ){
+    if( buf[index] != '0' )
+      last_dig = index - dp_index + 1;
+  }
+  return last_dig;
+}
+
 // Converts num to a string in buf, returns the number
 // of bytes that would be used if space permits (not including null)
 // or -1 on error
@@ -2656,9 +2678,32 @@ int _ftoa_core(char* buf, size_t buf_sz, double num,
   } else if( realfmt == 0 ) {
     if( precision < 0 ) {
       if( uppercase ) {
-        got = snprintf(buf, buf_sz, "%G", num);
+        // This if is necessary because if the number has
+        // 6 digits in the integer part, %g will not print
+        // the decimal part because the integer part have
+        // a number of digits equals to the standard precision.
+        if(num >= 100000.0 && num < 1000000.0){
+          got = snprintf(buf, buf_sz, "%.5E", num);
+          //Since we force the %.5e for maintain a precision of
+          //6 digits, the output could include some trailing zeroes.
+          //With _find_prec, we find how much digits we need.
+          //
+          //It can also be done starting from the number itself
+          //but this way avoids to deal with the loss of precision
+          //caused by floating point representation
+          if(buf_sz > 0)
+            got = snprintf(buf, buf_sz, "%.*E",_find_prec(buf, got), num);
+        }
+        else
+          got = snprintf(buf, buf_sz, "%G", num);
       } else {
-        got = snprintf(buf, buf_sz, "%g", num);
+        if(num >= 100000.0 && num < 1000000.0){
+          got = snprintf(buf, buf_sz, "%.5e", num);
+          if(buf_sz > 0)
+            got = snprintf(buf, buf_sz, "%.*e",_find_prec(buf, got), num);
+        }
+        else
+          got = snprintf(buf, buf_sz, "%g", num);
       }
     } else {
       if( uppercase ) {

test/io/panzone/real-writeln.chpl

@@ -0,0 +1,23 @@
+var a: real = 1.0;
+writeln("a = ", a);
+
+var b: real = 10.0;
+writeln("b = ", b);
+
+var c: real = 100.0;
+writeln("c = ", c);
+
+var d: real = 1000.0;
+writeln("d = ", d);
+
+var e: real = 10000.0;
+writeln("e = ", e);
+
+var f: real = 100000.0;
+writeln("f = ", f);
+
+var g: real = 1000000.0;
+writeln("g = ", g);
+
+var h: real =  100000.9;
+writeln("h = ", h);

test/io/panzone/real-writeln.good

@@ -0,0 +1,8 @@
+a = 1.0
+b = 10.0
+c = 100.0
+d = 1000.0
+e = 10000.0
+f = 1e+05
+g = 1e+06
+h = 1.00001e+05

test/modules/standard/math/acosh.good

@@ -4,7 +4,7 @@ b = 1.5
 acosh(b) = 0.962424
 c = 2.0
 acosh(c) = 1.31696
-d = 100000.0
+d = 1e+05
 acosh(d) = 12.2061
 e = 1e+09
 acosh(e) = 21.4164

test/modules/standard/memory/countMemory/countMemory.makegood

@@ -28,33 +28,38 @@ $realMemInKBytesVal = $realMemInBytesVal  / 1024;
 $realMemInMBytesVal = $realMemInKBytesVal / 1024;
 $realMemInGBytesVal = $realMemInMBytesVal / 1024;
 
-$realMemInBytes  = sprintf("%g", $realMemInBytesVal);
-$realMemInKBytes = sprintf("%g", $realMemInKBytesVal);
-$realMemInMBytes = sprintf("%g", $realMemInMBytesVal);
-$realMemInGBytes = sprintf("%g", $realMemInGBytesVal);
+$realMemInBytes  = print_chapel_real($realMemInBytesVal);
+$realMemInKBytes = print_chapel_real($realMemInKBytesVal);
+$realMemInMBytes = print_chapel_real($realMemInMBytesVal);
+$realMemInGBytes = print_chapel_real($realMemInGBytesVal);
 
-
-#
-# if a string is all digits, add a trailing .0 to match
-# Chapel's default formatting of reals
-#
-if ($realMemInBytes =~ m/^\d+$/) {
-    $realMemInBytes .= ".0";
-}
-if ($realMemInKBytes =~ m/^\d+$/) {
-    $realMemInKBytes .= ".0";
-}
-if ($realMemInMBytes =~ m/^\d+$/) {
-    $realMemInMBytes .= ".0";
-}
-if ($realMemInGBytes =~ m/^\d+$/) {
-    $realMemInGBytes .= ".0";
-}
-
-
 printf "memory is: %s\n", $realMemInBytes;
 printf " in bytes: %s\n", $realMemInBytes;
 printf "    in kb: %s\n", $realMemInKBytes;
 printf "    in mb: %s\n", $realMemInMBytes;
 printf "    in gb: %s\n", $realMemInGBytes;
 
+#
+# This is for change the formatting of a float number
+# to the Chapel's formatting of reals
+#
+sub print_chapel_real{
+	$retVal = 0;
+	if( ($_[0] >= 100000.0) and ($_[0] < 1000000.0) ){
+		$retVal = sprintf("%.5e", $_[0]);
+		$retVal =~ s/0+e/e/; #for removing the zeroes
+	}
+	else {
+		$retVal = sprintf("%g", $_[0]);
+	}
+
+	#
+	# if a string is all digits, add a trailing .0 to match
+	# Chapel's default formatting of reals
+	#
+	if ($retVal =~ m/^\d+$/) {
+	    $retVal .= ".0";
+	}
+
+	return $retVal;
+}

test/types/scalar/bradc/piVals.good

@@ -1,2 +1,2 @@
 x is: 3.14159e+08
-x is: 159265.0
+x is: 1.59265e+05

test/types/scalar/bradc/piVals1a.good

@@ -1,3 +1,3 @@
 x is: 3.14159e+08
 y is: 3.14159e+08
-x is: 159265.0
+x is: 1.59265e+05

test/types/scalar/bradc/piVals2.good

@@ -1,2 +1,2 @@
 x is: 3.14159e+08
-x is: 159265.0
+x is: 1.59265e+05

test/users/shetag/tensor.good

@@ -29,4 +29,4 @@ m4.setitem(2,2,100) = {n = 3, m = 6, a = 2.0 3.0 4.0 5.0 6.0 7.0
 3.0 100.0 5.0 6.0 7.0 8.0
 4.0 5.0 6.0 7.0 8.0 9.0}
 m4.mul(v3) = {n = 3, a = 270.0 1290.0 390.0}
-m4.rmul(v4) = {n = 6, a = 28200.0 337080.0 46920.0 56280.0 65640.0 75000.0}
+m4.rmul(v4) = {n = 6, a = 28200.0 3.3708e+05 46920.0 56280.0 65640.0 75000.0}