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From sebb <seb...@gmail.com>
Subject 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
Date Sun, 05 Apr 2009 17:25:54 GMT
On 05/04/2009, Phil Steitz <phil.steitz@gmail.com> wrote:
> sebb@apache.org 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?

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.

>  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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