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math.statistics: fix calculation of the harmonic mean

char-rename
Björn Lindqvist 2017-01-15 21:27:55 +01:00
parent 423181c867
commit 0701902122
3 changed files with 8 additions and 4 deletions
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5
basis/math/statistics/statistics-docs.factor
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@ -12,7 +12,7 @@ HELP: harmonic-mean
{ $values { "seq" sequence } { "x" "a non-negative real number" } }
{ $description "Computes the harmonic mean of the elements in " { $snippet "seq" } ". The harmonic mean is appropriate when the average of rates is desired." }
{ $notes "Positive reals only." }
{ $examples { $example "USING: math.statistics prettyprint ;" "{ 1 2 3 } harmonic-mean ." "6/11" } }
{ $examples { $example "USING: math.statistics prettyprint ;" "{ 1 2 3 } harmonic-mean ." "18/11" } }
{ $errors "Throws a " { $link signal-error. } " (divide by zero) if the sequence is empty." } ;
HELP: kth-smallest
@ -24,7 +24,8 @@ HELP: mean
{ $values { "seq" sequence } { "x" "a non-negative real number" } }
{ $description "Computes the arithmetic mean of the elements in " { $snippet "seq" } "." }
{ $examples { $example "USING: math.statistics prettyprint ;" "{ 1 2 3 } mean ." "2" } }
{ $errors "Throws a " { $link signal-error. } " (divide by zero) if the sequence is empty." } ;
{ $errors "Throws a " { $link signal-error. } " (divide by zero) if the sequence is empty." }
{ $see-also geometric-mean harmonic-mean } ;
HELP: median
{ $values { "seq" sequence } { "x" "a non-negative real number" } }

5
basis/math/statistics/statistics-tests.factor
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@ -13,7 +13,10 @@ IN: math.statistics.tests
{ 1.0 } [ { 1 1 1 } geometric-mean ] unit-test
{ t } [ 1000 1000 <array> geometric-mean 1000 .01 ~ ] unit-test
{ t } [ 100000 100000 <array> geometric-mean 100000 .01 ~ ] unit-test
{ 1/3 } [ { 1 1 1 } harmonic-mean ] unit-test
{ 1 } [ { 1 1 1 } harmonic-mean ] unit-test
{ 12/7 } [ { 1 2 4 } harmonic-mean ] unit-test
{ 5+1/4 } [ { 1 3 5 7 } contraharmonic-mean ] unit-test
{ 18 } [ { 4 8 15 16 23 42 } 0 trimmed-mean ] unit-test
{ 15+1/2 } [ { 4 8 15 16 23 42 } 0.2 trimmed-mean ] unit-test

2
basis/math/statistics/statistics.factor
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@ -35,7 +35,7 @@ IN: math.statistics
[ [ log ] map-sum ] [ length ] bi /f e^ ; inline
: harmonic-mean ( seq -- x )
[ recip ] map-sum recip ; inline
[ [ recip ] map-sum ] [ length swap / ] bi ; inline
: contraharmonic-mean ( seq -- x )
[ sum-of-squares ] [ sum ] bi / ; inline