per #1401 set highest sensitivity on low TT and halfBasal (#1403)

getting multiplication less or equal to 0 means that we have a really low target with a really low halfBasalTarget
with low TT and lowTTlowersSensitivity we need autosens_max as a value
we use multiplication instead of the division to avoid "division by zero error"

lib/determine-basal/determine-basal.js

@@ -244,7 +244,15 @@ var determine_basal = function determine_basal(glucose_status, currenttemp, iob_
  // e.g.: Sensitivity ratio set to 0.8 based on temp target of 120; Adjusting basal from 1.65 to 1.35; ISF from 58.9 to 73.6
  //sensitivityRatio = 2/(2+(target_bg-normalTarget)/40);
  var c = halfBasalTarget - normalTarget;
- sensitivityRatio = c/(c+target_bg-normalTarget);
+ // getting multiplication less or equal to 0 means that we have a really low target with a really low halfBasalTarget
+ // with low TT and lowTTlowersSensitivity we need autosens_max as a value
+ // we use multiplication instead of the division to avoid "division by zero error"
+ if (c * (c + target_bg-normalTarget) <= 0.0) {
+ sensitivityRatio = profile.autosens_max;
+ }
+ else {
+ sensitivityRatio = c/(c+target_bg-normalTarget);
+ }
  // limit sensitivityRatio to profile.autosens_max (1.2x by default)
  sensitivityRatio = Math.min(sensitivityRatio, profile.autosens_max);
  sensitivityRatio = round(sensitivityRatio,2);