leerho commented on code in PR #475:
URL: https://github.com/apache/datasketches-java/pull/475#discussion_r1408659590
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src/main/java/org/apache/datasketches/common/Util.java:
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@@ -550,56 +531,60 @@ public static double powerSeriesNextDouble(final int ppb,
final double curPoint,
}
/**
- * Computes the ceiling power of given <i>base</i> and <i>n</i> as doubles.
- * This is the smallest positive power
- * of <i>base</i> that equal to or greater than the given <i>n</i> and equal
to a mathematical integer.
+ * Returns the ceiling of a given <i>n</i> given a <i>radix</i>, where the
ceiling is an integral power of the radix.
+ * This is the smallest positive power of <i>radix</i> that is equal to or
greater than the given <i>n</i>
+ * and equal to a mathematical integer.
* The result of this function is consistent with {@link
#ceilingIntPowerOf2(int)} for values
* less than one. I.e., if <i>n < 1,</i> the result is 1.
*
- * @param base The base in the expression ⌈base<sup>n</sup>⌉.
+ * <p>The formula is:
<i>radix<sup>ceiling(log<sub>radix</sub>(x))</sup></i></p>
+ *
+ * @param radix The base of the number system.
* @param n The input argument.
- * @return the ceiling power of <i>base</i> as a double and equal to a
mathematical integer.
+ * @return the ceiling power of <i>radix</i> as a double and equal to a
mathematical integer.
*/
- public static double ceilingPowerBaseOfDouble(final double base, final
double n) {
+ public static double ceilingPowerBaseOfDouble(final double radix, final
double n) {
final double x = n < 1.0 ? 1.0 : n;
- return pow(base, ceil(logBaseOfX(base, x)));
+ return Math.round(pow(radix, ceil(logBaseOfX(radix, x))));
}
/**
- * Computes the floor power of given <i>base</i> and <i>n</i> as doubles.
- * This is the largest positive power
- * of <i>base</i> that equal to or less than the given n and equal to a
mathematical integer.
+ * Computes the floor of a given <i>n</i> given <i>radix</i>, where the
floor is an integral power of the radix.
+ * This is the largest positive power of <i>radix</i> that is equal to or
less than the given <i>n</i>
+ * and equal to a mathematical integer.
* The result of this function is consistent with {@link
#floorPowerOf2(int)} for values
* less than one. I.e., if <i>n < 1,</i> the result is 1.
*
- * @param base The base in the expression ⌊base<sup>n</sup>⌋.
+ * <p>The formula is:
<i>radix<sup>floor(log<sub>radix</sub>(x))</sup></i></p>
+ *
+ * @param radix The base of the number system.
* @param n The input argument.
* @return the floor power of 2 and equal to a mathematical integer.
*/
- public static double floorPowerBaseOfDouble(final double base, final double
n) {
+ public static double floorPowerBaseOfDouble(final double radix, final double
n) {
final double x = n < 1.0 ? 1.0 : n;
- return pow(base, floor(logBaseOfX(base, x)));
+ return Math.round(pow(radix, floor(logBaseOfX(radix, x))));
}
// Logarithm related
/**
- * The log base 2 of the value
+ * The log<sub>2</sub>(value)
* @param value the given value
- * @return The log base 2 of the value
+ * @return log<sub>2</sub>(value)
*/
public static double log2(final double value) {
return log(value) / LOG2;
}
/**
- * Returns the logarithm_logBase of x. Example: logB(2.0, x) = log(x) /
log(2.0).
- * @param logBase the base of the logarithm used
+ * Returns the log<sub>radix</sub>(x). Example: logB(2.0, x) = log(x) /
log(2.0).
Review Comment:
Jon already caught this. Will fix.
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