Re: svn commit: r762116 - in /commons/proper/math/trunk/src/java/org/apache/commons/math: ./ analysis/polynomials/ analysis/solvers/ estimation/ ode/ ode/nonstiff/ ode/sampling/ optimization/ random/ stat/ stat/descriptive/ stat/descriptive/moment/ s

Sun, 05 Apr 2009 11:30:43 -0700 

sebb wrote:

On 05/04/2009, Phil Steitz <[email protected]> wrote:

[email protected] wrote:

 We need to be careful with removing all of these casts.  They were inserted
earlier to eliminate some errors resulting from int/int computations in
larger expressions resulting in incorrect values.   Could be later JDKs
handle all of this seamlessly, but I would prefer to be safe rather than
sorry here and leave the explicit casts from int/long to double alone.


Are there any tests that expose these errors?
The ones we discovered, yes. IIRC, they were all of the form long/long or long*long embedded as below in a larger floating point computations. 
Seems to me that if an apparently unnecessary cast is included in the
code, this should also be documented so it is clear why it is there.

Or you could look at it as the cast itself as clarifying intent ;)

Phil

 Phil


Modified:

commons/proper/math/trunk/src/java/org/apache/commons/math/stat/regression/SimpleRegression.java

URL:

http://svn.apache.org/viewvc/commons/proper/math/trunk/src/java/org/apache/commons/math/stat/regression/SimpleRegression.java?rev=762116&r1=762115&r2=762116&view=diff
============================================================================== 
---

commons/proper/math/trunk/src/java/org/apache/commons/math/stat/regression/SimpleRegression.java
(original)

+++

commons/proper/math/trunk/src/java/org/apache/commons/math/stat/regression/SimpleRegression.java
Sun Apr  5 16:48:53 2009

@@ -124,11 +124,11 @@
        } else {
            double dx = x - xbar;
            double dy = y - ybar;
-            sumXX += dx * dx * (double) n / (double) (n + 1.0);
-            sumYY += dy * dy * (double) n / (double) (n + 1.0);
-            sumXY += dx * dy * (double) n / (double) (n + 1.0);
-            xbar += dx / (double) (n + 1.0);
-            ybar += dy / (double) (n + 1.0);
+            sumXX += dx * dx * n / (n + 1.0);
+            sumYY += dy * dy * n / (n + 1.0);
+            sumXY += dx * dy * n / (n + 1.0);
+            xbar += dx / (n + 1.0);
+            ybar += dy / (n + 1.0);
        }
        sumX += x;
        sumY += y;
@@ -157,11 +157,11 @@
        if (n > 0) {
            double dx = x - xbar;
            double dy = y - ybar;
-            sumXX -= dx * dx * (double) n / (double) (n - 1.0);
-            sumYY -= dy * dy * (double) n / (double) (n - 1.0);
-            sumXY -= dx * dy * (double) n / (double) (n - 1.0);
-            xbar -= dx / (double) (n - 1.0);
-            ybar -= dy / (double) (n - 1.0);
+            sumXX -= dx * dx * n / (n - 1.0);
+            sumYY -= dy * dy * n / (n - 1.0);
+            sumXY -= dx * dy * n / (n - 1.0);
+            xbar -= dx / (n - 1.0);
+            ybar -= dy / (n - 1.0);
            sumX -= x;
            sumY -= y;
            n--;
@@ -410,7 +410,7 @@
        if (n < 3) {
            return Double.NaN;
        }
-        return getSumSquaredErrors() / (double) (n - 2);
+        return getSumSquaredErrors() / (n - 2);
    }
      /**
@@ -468,7 +468,7 @@
     */
    public double getInterceptStdErr() {
        return Math.sqrt(
-            getMeanSquareError() * ((1d / (double) n) + (xbar * xbar) /

sumXX));

+            getMeanSquareError() * ((1d / n) + (xbar * xbar) / sumXX));
    }
      /**
@@ -589,7 +589,7 @@
    * @return the intercept of the regression line
    */
    private double getIntercept(double slope) {
-        return (sumY - slope * sumX) / ((double) n);
+        return (sumY - slope * sumX) / (n);
    }
      /**

Modified:

commons/proper/math/trunk/src/java/org/apache/commons/math/util/MathUtils.java

URL:

http://svn.apache.org/viewvc/commons/proper/math/trunk/src/java/org/apache/commons/math/util/MathUtils.java?rev=762116&r1=762115&r2=762116&view=diff
============================================================================== 
---

commons/proper/math/trunk/src/java/org/apache/commons/math/util/MathUtils.java
(original)

+++

commons/proper/math/trunk/src/java/org/apache/commons/math/util/MathUtils.java
Sun Apr  5 16:48:53 2009

@@ -307,7 +307,7 @@
            return 0;
        }
        if ((k == 1) || (k == n - 1)) {
-            return Math.log((double) n);
+            return Math.log(n);
        }
                /*
@@ -337,12 +337,12 @@
          // n!/(n-k)!
        for (int i = n - k + 1; i <= n; i++) {
-            logSum += Math.log((double) i);
+            logSum += Math.log(i);
        }
          // divide by k!
        for (int i = 2; i <= k; i++) {
-            logSum -= Math.log((double) i);
+            logSum -= Math.log(i);
        }
          return logSum;      @@ -523,7 +523,7 @@
        }
        double logSum = 0;
        for (int i = 2; i <= n; i++) {
-            logSum += Math.log((double)i);
+            logSum += Math.log(i);
        }
        return logSum;
    }

Modified:

commons/proper/math/trunk/src/java/org/apache/commons/math/util/TransformerMap.java

URL:

http://svn.apache.org/viewvc/commons/proper/math/trunk/src/java/org/apache/commons/math/util/TransformerMap.java?rev=762116&r1=762115&r2=762116&view=diff
============================================================================== 
---

commons/proper/math/trunk/src/java/org/apache/commons/math/util/TransformerMap.java
(original)

+++

commons/proper/math/trunk/src/java/org/apache/commons/math/util/TransformerMap.java
Sun Apr  5 16:48:53 2009

@@ -79,7 +79,7 @@
     * @return the mapped NumberTransformer or null.
     */
    public NumberTransformer getTransformer(Class<?> key) {
-        return (NumberTransformer) map.get(key);
+        return map.get(key);
    }
      /**





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