brackets and #write

[vsht]

I would like to use brackets to simplify the output of FORM before passing it to other programs. However,
it seems that the brackets do not survive a #write instruction, even if there is no intermediate sort inbetween. Consider for example

off statistics;
S a,b,z,y;
L exp = a*y^2 + 3*a + z*b+ z^3*b;
.sort
bracket a, b;
print exp;
#$a1 = exp;
#write <exp.frm> "%$",$a1;
.end

the print statement produces

   exp =
       + b * ( z + z^3 )

       + a * ( 3 + y^2 );

which is exactly what I want, but the content of my exp.frm is nevertheless

b*z+b*z^3+3*a+a*y^2

A naive workaround is to use a "fake" collect

off statistics;
S a,b,z,y;
CF head;
L exp = a*y^2 + 3*a + z*b+ z^3*b;
.sort
bracket a, b;
.sort
collect head;
.sort
print exp;
#$a1 = exp;
#write <exp.frm> "%$",$a1;
.end

and remove head in a later step. However, this probably would not work for very large expressions and in general appears to be an ugly hack. I believe that I'm not the first person to encounter this complication, so I wonder what is the recommended workaround.

Cheers,
Vladyslav

[vermaseren]

Hi, The bracket statement does not work for dollar expressions. If you use %e instead, at least for me it works. As in: S a,b,c; L F = (a+b+c)^10; B b; .sort #write <atest> " F = %e",F .end What goes wrong in your code is also that the preprocessor gets to do its thing before the ‘algebra’ run. Hence, the #write gets executed before your expression has passed the running and hence the bracketting. Cheers Jos

…

On 8 Feb 2018, at 07:31, Vladyslav Shtabovenko ***@***.***> wrote: I would like to use brackets to simplify the output of FORM before passing it to other programs. However, it seems that the brackets do not survive a #write instruction, even if there is no intermediate sort inbetween. Consider for example off statistics; S a,b,z,y; L exp = a*y^2 + 3*a + z*b+ z^3*b; .sort bracket a, b; print exp; #$a1 = exp; #write <exp.frm> "%$",$a1; .end the print statement produces exp = + b * ( z + z^3 ) + a * ( 3 + y^2 ); which is exactly what I want, but the content of my exp.frm is nevertheless b*z+b*z^3+3*a+a*y^2 A naive workaround is to use a "fake" collect off statistics; S a,b,z,y; CF head; L exp = a*y^2 + 3*a + z*b+ z^3*b; .sort bracket a, b; .sort collect head; .sort print exp; #$a1 = exp; #write <exp.frm> "%$",$a1; .end and remove head in a later step. However, this probably would not work for very large expressions and in general appears to be an ugly hack. I believe that I'm not the first person to encounter this complication, so I wonder what is the recommended workaround. Cheers, Vladyslav — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#262>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AFLxEibrvQW50SrSkIfOybiNmCF_AJbCks5tSpS5gaJpZM4R93Vk>.

[vsht]

Perfect, many thanks!