Your vague instinct is correct. From the top of the perdoc for Math::Pari: 
By default the package exports functions PARI(), PARIcol(), PARIvar(),
+ PARImat() and PARImat_tr() which convert their argument(s) to a PARI
+ object. (In fact PARI() is just an alias for new Math::Pari). The fu
+nction PARI() accepts following data as its arguments

One integer

    Is converted to a PARI integer.
One float

    Is converted to a PARI float.
One string

    Is executed as a PARI expresion (so should not contain whitespace)
+.
PARI object

    Is passed unchanged.
Reference to a Perl array

    Each element is converted using the same rules, PARI vector-row wi
+th these elements is returned.

...

Conflicts of rules in PARI()

    In deciding what rule of the above to apply the preference is give
+n to the uppermost choice of those available now. If none matches, th
+en the string rule is used. So PARI(1) returns integer, PARI(1.) retu
+rns float, PARI("1") evaluates 1 as a PARI expression (well, the resu
+lt is the same as PARI(1), only slower).

[download]
So numbers with a decimal point are always interpreted as floats.

An alternative method for insuring integer objects is to int Perl variables before converting to Pari objects.

-Mark

In reply to Re: On precision in Math::Pari by kvale
in thread On precision in Math::Pari by tlm

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