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From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: net.unix-wizards
Subject: Re: Unsigned -> float conversion
Message-ID: <2351@brl-smoke.ARPA>
Date: Fri, 4-Apr-86 03:56:19 EST
Article-I.D.: brl-smok.2351
Posted: Fri Apr  4 03:56:19 1986
Date-Received: Tue, 8-Apr-86 06:16:59 EST
References: <144@daisy.warwick.UUCP>
Reply-To: gwyn@brl.ARPA
Organization: Ballistic Research Lab (BRL)
Lines: 29

In article <144@daisy.warwick.UUCP> cudcv@daisy.warwk.ac.uk (Rob McMahon) writes:
>main()
>{
>	unsigned long u;
>	double d;
>	float f;
>
>	u = ~0;
>	d = u;
>	f = u;
>	printf("u = %lu f = %f d = %lf\n", u, f, d);
>	if (d < 0) printf("d < 0\n");
>	if (f < 0) printf("f < 0\n");
>}
>
>On a VAX-780 running 4.2bsd or a Sun-2 running 2.0 it gives
>
>u = 4294967295 f = -1.000000 d = -1.000000
>d < 0
>f < 0
>
>On a Gould PN6000 running UTX/32 1.2 it gives
>
>
>u = 4294967295 f = -1.000000 d = 4294967295.000000
>f < 0

The Gould almost got it right; f should also be a large number,
approximately the same as d.  The SVR2 VAX PCC gets it right.