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Document division by zero behavior

darcs
slava 2006-09-16 19:57:07 +00:00
parent ef865ffd96
commit 6bd500c34b
3 changed files with 19 additions and 14 deletions
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10
TODO.FACTOR.txt
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@ -15,6 +15,7 @@
- track individual method usages - track individual method usages
- variable width word wrap - variable width word wrap
- add-gadget, model-changed, set-model should compile - add-gadget, model-changed, set-model should compile
- set-model set-model* and control-changed: its a hack, clean it up
- graphical module manager tool - graphical module manager tool
- editor: - editor:
- more efficient multi-line inserts - more efficient multi-line inserts
@ -22,17 +23,16 @@
space space
- we have trouble drawing rectangles - we have trouble drawing rectangles
- ui browser: show currently selected vocab & words - ui browser: show currently selected vocab & words
- the editor should fill up the interior of the scroller completely
- doc sweep - doc sweep
- tool help - tool help
- perhaps commands window should sort by gesture - perhaps commands window should sort by gesture
- merge keyboard help with help in some way - merge keyboard help with help in some way
- keyboard help: hide commands whose gestures are shadowed - keyboard help: hide commands whose gestures are shadowed
- division by zero may not raise an error -- document this
- the editor should fill up the interior of the scroller completely
+ ui: + ui:
- help tool: edit, reload buttons
- words: - words:
- S+left: reload - S+left: reload
- S+right: inspect - S+right: inspect
@ -46,7 +46,6 @@
- page scrolling should be timer-based too - page scrolling should be timer-based too
- invoking interactor commands when interactor is busy -- still fucked - invoking interactor commands when interactor is busy -- still fucked
because of grafting and ungrafting because of grafting and ungrafting
- set-model set-model* and control-changed: its a hack, clean it up
- x11: scroll up/down wiggles caret - x11: scroll up/down wiggles caret
- roundoff is still not quite right with tracks - roundoff is still not quite right with tracks
- fix top level window positioning - fix top level window positioning
@ -78,7 +77,8 @@
- horizontal wheel scrolling - horizontal wheel scrolling
- polish OS X menu bar code - polish OS X menu bar code
- structure editor - structure editor
- mouse over for input: - mouse over for input w/ multiple lines looks stupid
+ module system: + module system:
- convention for main entry point of a module - convention for main entry point of a module

9
doc/handbook/math.facts
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@ -17,6 +17,13 @@ ARTICLE: "number-types" "Types of numbers"
{ $subsection "floats" } { $subsection "floats" }
{ $subsection "complex-numbers" } ; { $subsection "complex-numbers" } ;
ARTICLE: "division-by-zero" "Division by zero"
"Floating point division never raises an error if the denominator is zero. This means that if at least one of the two inputs to " { $link / } ", " { $link /f } " or " { $link mod } " is a float, the result will be a floating point infinity or not a number value."
$terpri
"The behavior of integer division is hardware specific. On x86 processors, " { $link /i } " and " { $link mod } " raise an error if both inputs are integers and the denominator is zero. On PowerPC, integer division by zero yields a result of zero."
$terpri
"On the other hand, the " { $link / } " word, when given integer arguments, implements a much more expensive division algorithm which always yields an exact rational answer, and this word always tests for division by zero explicitly." ;
ARTICLE: "number-protocol" "Number protocol" ARTICLE: "number-protocol" "Number protocol"
"Math operations obey certain numerical upgrade rules. If one of the inputs is a bignum and the other is a fixnum, the latter is first coerced to a bignum; if one of the inputs is a float, the other is coerced to a float." "Math operations obey certain numerical upgrade rules. If one of the inputs is a bignum and the other is a fixnum, the latter is first coerced to a bignum; if one of the inputs is a float, the other is coerced to a float."
$terpri $terpri
@ -29,7 +36,7 @@ $terpri
{ $subsection * } { $subsection * }
{ $subsection / } { $subsection / }
"Non-commutative operations take operands from the stack in the natural order; " { $snippet "6 2 /" } " divides 6 by 2." "Non-commutative operations take operands from the stack in the natural order; " { $snippet "6 2 /" } " divides 6 by 2."
$terpri { $subsection "division-by-zero" }
"Real numbers (but not complex numbers) can be ordered:" "Real numbers (but not complex numbers) can be ordered:"
{ $subsection < } { $subsection < }
{ $subsection <= } { $subsection <= }

14
library/math/math.facts
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@ -68,7 +68,7 @@ HELP: /
"Division of ratios and complex numbers proceeds using the relevant mathematical rules." "Division of ratios and complex numbers proceeds using the relevant mathematical rules."
} }
} }
{ $errors "Throws an error if both inputs are integers, and the denominator is 0." } ; { $see-also "division-by-zero" } ;
HELP: /i HELP: /i
{ $values { "x" "a real number" } { "y" "a real number" } { "z" "a real number" } } { $values { "x" "a real number" } { "y" "a real number" } { "z" "a real number" } }
@ -81,7 +81,7 @@ HELP: /i
"Integer division of ratios and complex numbers proceeds using the relevant mathematical rules." "Integer division of ratios and complex numbers proceeds using the relevant mathematical rules."
} }
} }
{ $errors "Throws an error if both inputs are integers, and the denominator is 0." } ; { $see-also "division-by-zero" } ;
HELP: /f HELP: /f
{ $values { "x" "a real number" } { "y" "a real number" } { "z" "a real number" } } { $values { "x" "a real number" } { "y" "a real number" } { "z" "a real number" } }
@ -94,7 +94,7 @@ HELP: /f
"Integer division of ratios and complex numbers proceeds using the relevant mathematical rules." "Integer division of ratios and complex numbers proceeds using the relevant mathematical rules."
} }
} }
{ $errors "Throws an error if both inputs are integers, and the denominator is 0." } ; { $see-also "division-by-zero" } ;
HELP: mod HELP: mod
{ $values { "x" "an integer" } { "y" "an integer" } { "z" "an integer" } } { $values { "x" "an integer" } { "y" "an integer" } { "z" "an integer" } }
@ -105,8 +105,7 @@ HELP: mod
"Modulus of bignums always yields a bignum." "Modulus of bignums always yields a bignum."
} }
} }
{ $errors "Throws an error if the denominator is 0." } { $see-also "division-by-zero" rem } ;
{ $see-also rem } ;
HELP: /mod HELP: /mod
{ $values { "x" "an integer" } { "y" "an integer" } { "z" "an integer" } { "w" "an integer" } } { $values { "x" "an integer" } { "y" "an integer" } { "z" "an integer" } { "w" "an integer" } }
@ -117,7 +116,7 @@ HELP: /mod
"The quotient and remainder of two bignums is always a bignum." "The quotient and remainder of two bignums is always a bignum."
} }
} }
{ $errors "Throws an error if the denominator is 0." } ; { $see-also "division-by-zero" } ;
HELP: bitand HELP: bitand
{ $values { "x" "an integer" } { "y" "an integer" } { "z" "an integer" } } { $values { "x" "an integer" } { "y" "an integer" } { "z" "an integer" } }
@ -225,8 +224,7 @@ HELP: rem
"Modulus of bignums always yields a bignum." "Modulus of bignums always yields a bignum."
} }
} }
{ $errors "Throws an error if the denominator is 0." } { $see-also "division-by-zero" mod } ;
{ $see-also mod } ;
HELP: sgn HELP: sgn
{ $values { "x" "a real number" } { "n" "-1, 0 or 1" } } { $values { "x" "a real number" } { "n" "-1, 0 or 1" } }