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# testnfreq()

Usage:
 ```testnfreq(nfreq), nfreq a vector of positive integers ```

Keywords: fourier transforms
```testnfreq(nfreq) returns a LOGICAL vector the same length as nfreq, a
vector of positive integers.  Element j of the result is True if and
only if nfreq[j] has no prime factors > 29.

testnfreq() is useful in macros which use one of the fast Fourier
transform functions, rft(), dft() and hft(), since these operate only on
vectors or matrices x for which nrows(x) has no prime factors > 29.  It
allows you to test whether this condition is true.

The use of testnfreq() is deprecated since goodfactors() can be used in
an equivalent test.  When N is a scalar, goodfactors(N) == N is True if
and only if testnfreq(N) is true.  Moreover, the value of goodfactors(N)
is the next integer >= N with no prime factors > 29.

Example:
if (!testnfreq(nrows(y))){
error("nrows(y) has prime factor > 29")
}else{
yft <- rft(y)
}