[vwnc] Floats and NaNs

Hi,

On a windows image runnig VW 7.5, trying to print a NaN causes infinite
recursion, and eventually crashes the image.

bytes := #[ 255 255 255 255].
nanFloat := Float basicNew.
bytes doWithIndex: [:b :i | nanFloat basicAt: i put: b].

nanFloat printString
=> causes infinite recursion as #printOn:digits: calls #negated which in
turn tries to do an arithmetic operation on a NaN. As the primitive fails,
the double dispatch takes on and #abs is called on the NaN which in turns
calls #negated again.

Debug It
Float>>differenceFromFloat:
Float>>-
Float(ArithmeticValue)>>negated
Float(ArithmeticValue)>>abs
Float>>differenceFromFloat:
Float>>-
Float(ArithmeticValue)>>negated
Float(LimitedPrecisionReal)>>printOn:digits:
Float(LimitedPrecisionReal)>>printOn:
Float(Object)>>printString

My proposed fix is as follows:

Number >> isNaN
        ^false

Float >> isNaN
        ^self exponent = 128

Double >> isNaN
        ^self exponent = 1024

LimitedPrecissionReal >> printOn: aStream digits: digits
        self > 0.0 ifTrue:
                [^self absPrintOn: aStream digits: digits].
        self = 0.0 ifTrue:
                [aStream nextPutAll: '0.0'.
                ^self class == Float ifFalse: [aStream nextPut: self class
exponentCharacter]].
        self isNaN ifTrue:
                [^aStream nextPutAll: 'NaN'].
        self < 0.0 ifTrue:
                [aStream nextPutAll: '-'.
                ^self negated absPrintOn: aStream digits: digits].
        self error: 'mysterious number'





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that might affect any computer system into which it is received and
opened, it is the responsibility of the recipient to ensure that it
is virus free and no responsibility is accepted by JPMorgan Chase &
Co., its subsidiaries and affiliates, as applicable, for any loss
or damage arising in any way from its use. If you received this
transmission in error, please immediately contact the sender and
destroy the material in its entirety, whether in electronic or hard
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You should load the "IEEE Math" parcel that in 7.5 is in the
Preview/parcels directory.  The parcel modifies the image to prevent
this infinite recursion in printing among other problems.  

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On
Behalf Of [hidden email]
Sent: Friday, February 22, 2008 5:15 AM
To: [hidden email]
Cc: [hidden email]
Subject: [vwnc] Floats and NaNs


Hi,

On a windows image runnig VW 7.5, trying to print a NaN causes infinite
recursion, and eventually crashes the image.

bytes := #[ 255 255 255 255].
nanFloat := Float basicNew.
bytes doWithIndex: [:b :i | nanFloat basicAt: i put: b].

nanFloat printString
=> causes infinite recursion as #printOn:digits: calls #negated which in

turn tries to do an arithmetic operation on a NaN. As the primitive
fails,
the double dispatch takes on and #abs is called on the NaN which in
turns
calls #negated again.

Debug It
Float>>differenceFromFloat:
Float>>-
Float(ArithmeticValue)>>negated
Float(ArithmeticValue)>>abs
Float>>differenceFromFloat:
Float>>-
Float(ArithmeticValue)>>negated
Float(LimitedPrecisionReal)>>printOn:digits:
Float(LimitedPrecisionReal)>>printOn:
Float(Object)>>printString

My proposed fix is as follows:

Number >> isNaN
        ^false

Float >> isNaN
        ^self exponent = 128

Double >> isNaN
        ^self exponent = 1024

LimitedPrecissionReal >> printOn: aStream digits: digits
        self > 0.0 ifTrue:
                [^self absPrintOn: aStream digits: digits].
        self = 0.0 ifTrue:
                [aStream nextPutAll: '0.0'.
                ^self class == Float ifFalse: [aStream nextPut: self
class
exponentCharacter]].
        self isNaN ifTrue:
                [^aStream nextPutAll: 'NaN'].
        self < 0.0 ifTrue:
                [aStream nextPutAll: '-'.
                ^self negated absPrintOn: aStream digits: digits].
        self error: 'mysterious number'





Generally, this communication is for informational purposes only
and it is not intended as an offer or solicitation for the purchase
or sale of any financial instrument or as an official confirmation
of any transaction. In the event you are receiving the offering
materials attached below related to your interest in hedge funds or
private equity, this communication may be intended as an offer or
solicitation for the purchase or sale of such fund(s).  All market
prices, data and other information are not warranted as to
completeness or accuracy and are subject to change without notice.
Any comments or statements made herein do not necessarily reflect
those of JPMorgan Chase & Co., its subsidiaries and affiliates.

This transmission may contain information that is privileged,
confidential, legally privileged, and/or exempt from disclosure
under applicable law. If you are not the intended recipient, you
are hereby notified that any disclosure, copying, distribution, or
use of the information contained herein (including any reliance
thereon) is STRICTLY PROHIBITED. Although this transmission and any
attachments are believed to be free of any virus or other defect
that might affect any computer system into which it is received and
opened, it is the responsibility of the recipient to ensure that it
is virus free and no responsibility is accepted by JPMorgan Chase &
Co., its subsidiaries and affiliates, as applicable, for any loss
or damage arising in any way from its use. If you received this
transmission in error, please immediately contact the sender and
destroy the material in its entirety, whether in electronic or hard
copy format. Thank you.
Please refer to http://www.jpmorgan.com/pages/disclosures for
disclosures relating to UK legal entities.
_______________________________________________
vwnc mailing list
[hidden email]
http://lists.cs.uiuc.edu/mailman/listinfo/vwnc


_______________________________________________
vwnc mailing list
[hidden email]
http://lists.cs.uiuc.edu/mailman/listinfo/vwnc