locale independent printing for doubles when they are part of an abstract expression

src/runtime/c/gu/string.c

@@ -217,6 +217,29 @@ gu_string_to_double(GuString s, double *res)
 	return true;
 }
 
+void
+gu_double_to_string(double val, GuOut* out, GuExn* err)
+{
+	int ival = (int) val;
+    gu_printf(out, err, "%d", ival);
+    val -= ival;
+
+	if (val < 0)
+		val = -val;
+
+	if (val != 0) {
+		gu_putc('.', out, err);
+
+		while (val > 0.000001)  // process remaining digits
+		{
+			val  = val * 10;
+			ival = (int) val;
+			gu_printf(out, err, "%d", ival);
+			val -= ival;
+		}
+	}
+}
+
 bool
 gu_string_is_prefix(GuString s1, GuString s2)
 {

src/runtime/c/gu/string.h

@@ -48,6 +48,9 @@ gu_string_to_int(GuString s, int *res);
 bool
 gu_string_to_double(GuString s, double *res);
 
+void
+gu_double_to_string(double val, GuOut* out, GuExn* err);
+
 bool
 gu_string_is_prefix(GuString s1, GuString s2);
 

src/runtime/c/pgf/expr.c

@@ -1189,7 +1189,7 @@ pgf_print_literal(PgfLiteral lit,
     }
 	case PGF_LITERAL_FLT: {
         PgfLiteralFlt* lit = ei.data;
-		gu_printf(out, err, "%lg", lit->val);
+		gu_double_to_string(lit->val, out, err);
         break;
     }
 	default: