First round of fixes of log scaling based on code review from danvk.

diff --git a/dygraph-canvas.js b/dygraph-canvas.js
index fc7ab1d..245dc6f 100644 (file)
--- a/dygraph-canvas.js
+++ b/dygraph-canvas.js
@@ -89,7 +89,7 @@ DygraphLayout.prototype._evaluateLimits = function() {
     axis.yrange = axis.maxyval - axis.minyval;
     axis.yscale = (axis.yrange != 0 ? 1.0 / axis.yrange : 1.0);
 
-    axis.ylogrange = Math.log(axis.maxyval) - Math.log(axis.minyval);
+    axis.ylogrange = Dygraph.log10(axis.maxyval) - Dygraph.log10(axis.minyval);
     axis.ylogscale = (axis.ylogrange != 0 ? 1.0 / axis.ylogrange : 1.0);
   }
 };
@@ -108,7 +108,7 @@ DygraphLayout.prototype._evaluateLineCharts = function() {
       
       var yval;
       if (this.dygraph_.attr_("logscale")) {
-        yval = 1.0 - ((Math.log(parseFloat(item[1])) - Math.log(axis.minyval)) * axis.ylogscale); // really should just be yscale.
+        yval = 1.0 - ((Dygraph.log10(parseFloat(item[1])) - Dygraph.log10(axis.minyval)) * axis.ylogscale); // really should just be yscale.
       } else {
         yval = 1.0 - ((parseFloat(item[1]) - axis.minyval) * axis.yscale);
       }

diff --git a/dygraph.js b/dygraph.js
index 9826414..5b35b8a 100644 (file)
--- a/dygraph.js
+++ b/dygraph.js
@@ -80,9 +80,9 @@ Dygraph.DEFAULT_HEIGHT = 320;
 Dygraph.AXIS_LINE_WIDTH = 0.3;
 
 Dygraph.LOG_SCALE = 10;
-Dygraph.LOG_BASE_E_OF_TEN = Math.log(Dygraph.LOG_SCALE);
+Dygraph.LN_TEN = Math.log(Dygraph.LOG_SCALE);
 Dygraph.log10 = function(x) {
-  return Math.log(x) / Dygraph.LOG_BASE_E_OF_TEN;
+  return Math.log(x) / Dygraph.LN_TEN;
 }
 
 // Default attribute values.
@@ -372,8 +372,8 @@ Dygraph.prototype.toDomCoords = function(x, y, axis) {
 /**
  * Convert from data x coordinates to canvas/div X coordinate.
  * If specified, do this conversion for the coordinate system of a particular
- * axis. Uses the first axis by default.
- * returns a single value or null if x is null.
+ * axis.
+ * Returns a single value or null if x is null.
  */
 Dygraph.prototype.toDomXCoord = function(x) {
   if (x == null) {

diff --git a/tests/logscale.html b/tests/logscale.html
index 9c17ead..30e4a32 100644 (file)
--- a/tests/logscale.html
+++ b/tests/logscale.html
@@ -41,7 +41,7 @@
         g.updateOptions({ logscale : true });
       }
       function linearScale() {
-        g.updateOptions({ logscale : null });
+        g.updateOptions({ logscale : false });
       }
     </script>