diff -r f433193f7bb6 -r 08c92cb740b9 www/js/global.js
--- a/www/js/global.js	Sat Nov 17 15:58:13 2018 +0100
+++ b/www/js/global.js	Sat Nov 17 19:44:39 2018 +0100
@@ -84,15 +84,20 @@
 
 
 function ebc_to_srm(ebc) {
-	return  -1.32303E-12 * Math.pow(ebc, 4) - 0.00000000291515 * Math.pow(ebc, 3) + 0.00000818515 * Math.pow(ebc, 2) + 0.372038 * ebc + 0.596351;
+	var srm = -1.32303E-12 * Math.pow(ebc, 4) - 0.00000000291515 * Math.pow(ebc, 3) + 0.00000818515 * Math.pow(ebc, 2) + 0.372038 * ebc + 0.596351;
+	if ((ebc < 0) || (srm < 0))
+		console.log("ebc_to_srm("+ebc+") = "+srm);
+	return srm
 }
 
 
 
 function srm_to_ebc(srm)
 {
-	var ebc = 0.000000000176506 * Math.pow(srm, 4) + 0.000000154529 * Math.pow(srm, 3) - 0.000159428 * Math.pow(srm, 2) + 2.68837 * srm - 1.6004;
-	return Math.round(ebc);
+	var ebc = Math.round(0.000000000176506 * Math.pow(srm, 4) + 0.000000154529 * Math.pow(srm, 3) - 0.000159428 * Math.pow(srm, 2) + 2.68837 * srm - 1.6004);
+	if ((ebc < 0) || (srm < 0))
+		console.log("srm_to_ebc("+srm+") = "+ebc);
+	return ebc;
 }