Re: IsExact

• To: mathgroup at smc.vnet.net
• Subject: [mg80553] Re: [mg80523] IsExact
• From: Daniel Lichtblau <danl at wolfram.com>
• Date: Sun, 26 Aug 2007 02:59:07 -0400 (EDT)
• References: <200708240600.CAA16662@smc.vnet.net>

```carlos at colorado.edu wrote:
> Let c be a 1D list of scalar coefficients, numeric or symbolic,
> real or complex. No entry is a list. Examples:
>
> ClearAll[n,x,y,a,a1,a2,b,r];
> c1={1,2*I/5,E^(25*n),3/4+I,Cos[n*x*Pi],y*Sqrt[-5]};
> c2={a/b,r+2/5,a1,,,,,a2};
> c3={1.5,0,Sqrt[3],0,4};
> c4={(r+0.5)/3,3/7,3+Sin[4*x*y]};
> c5={1,2,3,4,5,6}+0.0;
> c6={N[x]};
>
> I need a function IsExact[c] that returns False if
> at least one entry of c is floating, or if it contains one
> floating number; else True.  For example, tests on
> c1 and c2  should return True; the others False.
>
> Any simple way to implement this? It should work on V.5.
> Thanks.
>

IsExact[c_]:=Internal`EffectivePrecision[c]===Infinity

Note that c6 is in fact exact, because N[x] is still (the symbol) x.

Daniel Lichtblau
Wolfram Research

```

• References:
• IsExact
• From: carlos@colorado.edu
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