#272 Taylor sometimes prints without ellipses

[Stavros Macrakis]

The ellipsis (+...) is sometimes not displayed on Taylor
series, in particular:

taylor(1,x,0,3)+x^3
taylor(1,x,0,3)*x

even though TaylorInfo shows the truncation information,
it is used for subsequent calculations, and /T/ appears
in the display.

More detail.

Setup---------------------

zero:taylor(0,x,0,3)
one: taylor(1,x,0,3).
onex3: taylor(1+x^3,x,0,3)

Incorrect cases------------------------------------------------

zero+x^3 => x^3
one*x => x
one+x^3 => 1+x^3
(one+x^3)-1 => x^3

Correct cases------------------------------------------------

zero => 0+...
one => 1+...
one+x^4 => 1+...
zero*x => 0+...
one*x-x => 0+...
(one+x^3)-x^3 => 1+...

onex3 => 1+x^3+...
onex3-1 => x^3+...

[Stavros Macrakis]

Logged In: YES
user_id=588346

The above is true with psexpand:false (the default).
Other values of psexpand correct some of the incorrect cases:
With psexpand:true, they are all displayed correctly.
With psexpand:multi, one of the four incorrect cases,
one+x^3, is displayed correctly.

The core of the problem seems to be in psdisrep(hayat). But
the logic around TRUNC and PS in form-mrat(nforma) is
confusing -- what exactly do TRUNC and PS mean separately
and together?