Fix ExponentialRamp exception

Negative input could cause a crash.

Fixes #92

1 files changed, 9 insertions, 9 deletions

diff --git a/src/main/java/com/jsyn/unitgen/ExponentialRamp.java b/src/main/java/com/jsyn/unitgen/ExponentialRamp.java
index 36159b4..6917126 100644
--- a/src/main/java/com/jsyn/unitgen/ExponentialRamp.java
+++ b/src/main/java/com/jsyn/unitgen/ExponentialRamp.java
@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *     http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -21,7 +21,7 @@ import com.jsyn.ports.UnitVariablePort;
 
 /**
  * Output approaches Input exponentially and will reach it in the specified time.
- * 
+ *
  * @author Phil Burk (C) 2010 Mobileer Inc
  * @version 016
  * @see LinearRamp
@@ -35,10 +35,11 @@ public class ExponentialRamp extends UnitFilter {
     private double target;
     private double timeHeld = 0.0;
     private double scaler = 1.0;
+    private double MIN_VALUE = 0.00001;
 
     public ExponentialRamp() {
         addPort(time = new UnitInputPort("Time"));
-        input.setup(0.0001, 1.0, 1.0);
+        input.setup(MIN_VALUE, 1.0, 1.0);
         addPort(current = new UnitVariablePort("Current", 1.0));
     }
 
@@ -49,6 +50,10 @@ public class ExponentialRamp extends UnitFilter {
         double currentTime = time.getValues()[0];
         double currentValue = current.getValue();
 
+        // Clip input values to prevent illegal values close to zero or negative.
+        currentInput = Math.max(MIN_VALUE, currentInput);
+        currentValue = Math.max(MIN_VALUE, currentValue);
+
         if (currentTime != timeHeld) {
             scaler = convertTimeToExponentialScaler(currentTime, currentValue, currentInput);
             timeHeld = currentTime;
@@ -92,11 +97,6 @@ public class ExponentialRamp extends UnitFilter {
     }
 
     private double convertTimeToExponentialScaler(double duration, double source, double target) {
-        double product = source * target;
-        if (product <= 0.0000001) {
-            throw new IllegalArgumentException(
-                    "Exponential ramp crosses zero or gets too close to zero.");
-        }
         // Calculate scaler so that scaler^frames = target/source
         double numFrames = duration * getFrameRate();
         return Math.pow((target / source), (1.0 / numFrames));