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math.functions: adding "round-to".

db4
John Benediktsson 2013-01-30 09:41:21 -08:00
parent 5a7e7b8d9b
commit 422ccf9901
3 changed files with 29 additions and 0 deletions
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10
basis/math/functions/functions-docs.factor
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@ -40,6 +40,7 @@ ARTICLE: "arithmetic-functions" "Arithmetic functions"
floor floor
truncate truncate
round round
round-to
} }
"Inexact comparison:" "Inexact comparison:"
{ $subsections ~ } { $subsections ~ }
@ -328,6 +329,15 @@ HELP: round
{ $description "Outputs the whole number closest to " { $snippet "x" } "." } { $description "Outputs the whole number closest to " { $snippet "x" } "." }
{ $notes "The result is not necessarily an integer." } ; { $notes "The result is not necessarily an integer." } ;
HELP: round-to
{ $values { "x" real } { "n" integer } { "y" real } }
{ $description "Outputs the number closest to " { $snippet "x" } ", rounded to " { $snippet "n" } " decimals." }
{ $notes "The result is not necessarily an integer." }
{ $examples
{ $example "USING: math.functions prettyprint ;" "1.23456 2 round-to ." "1.23" }
{ $example "USING: math.functions prettyprint ;" "12345.6789 -3 round-to ." "12000.0" }
} ;
HELP: roots HELP: roots
{ $values { "x" number } { "t" integer } { "seq" sequence } } { $values { "x" number } { "t" integer } { "seq" sequence } }
{ $description "Outputs the " { $snippet "t" } " roots of a number " { $snippet "x" } "." } { $description "Outputs the " { $snippet "t" } " roots of a number " { $snippet "x" } "." }

16
basis/math/functions/functions-tests.factor
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@ -255,3 +255,19 @@ CONSTANT: log10-factorial-1000 0x1.40f3593ed6f8ep11
{ -1.0 } [ -1 -0.0 copysign ] unit-test { -1.0 } [ -1 -0.0 copysign ] unit-test
{ 1.5 } [ -1.5 2 copysign ] unit-test { 1.5 } [ -1.5 2 copysign ] unit-test
{ -1.5 } [ -1.5 -2 copysign ] unit-test { -1.5 } [ -1.5 -2 copysign ] unit-test
{ 0.0 } [ 0 2 round-to ] unit-test
{ 1.0 } [ 1 2 round-to ] unit-test
{ 1.23 } [ 1.2349 2 round-to ] unit-test
{ 1.24 } [ 1.2350 2 round-to ] unit-test
{ 1.24 } [ 1.2351 2 round-to ] unit-test
{ -1.23 } [ -1.2349 2 round-to ] unit-test
{ -1.24 } [ -1.2350 2 round-to ] unit-test
{ -1.24 } [ -1.2351 2 round-to ] unit-test
{
{
0.0 0.0 10000.0 12000.0 12300.0 12350.0 12346.0 12345.7
12345.68 12345.679 12345.6789 12345.6789 12345.678901
12345.6789012 12345.67890123 12345.678901235
}
} [ 12345.67890123456 -6 9 [a,b] [ round-to ] with map ] unit-test

3
basis/math/functions/functions.factor
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@ -396,3 +396,6 @@ M: float copysign
[ double>bits ] [ fp-sign ] bi* [ double>bits ] [ fp-sign ] bi*
[ 63 2^ bitor ] [ 63 2^ bitnot bitand ] if [ 63 2^ bitor ] [ 63 2^ bitnot bitand ] if
bits>double ; bits>double ;
: round-to ( x n -- y )
10^ [ * 0.5 over 0 > [ + ] [ - ] if truncate ] [ / ] bi ;