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Is there an easy way to collect terms by powers of a variable in an expression? Ie. I have an expression on the stack that looks like this
A*x^2 + A*x + B*x + C
I want to group (something like GROUP(expression,'x') ) it by powers of x, so that it looks like this:
Ax^2 + (A+B)x + C
and not something like A(x^2 + x) + Bx + C which FACTOR/SIMPLIFY/COLLECT often give me.
It would also be handy if I could extract a vector of coefficients from that expression: [A A+B C].
If anyone knows how to do this please help me out :)
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I think I've found what I was looking for - the function A->P from the Polynomial library by Steen S. Schmidt.
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For A*X^2 + A*X + B*x + C try using COLLECT alone and you should get A*X^2 + (B+C)*X + C as desired.
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Quote:
For A*X^2 + A*X + B*x + C try using COLLECT alone and you should get A*X^2 + (B+C)*X + C as desired.
That would be quite remarkable!
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I'm using a real HP50g with rom 2.15 and flag settings as follows:
{
# 80800002452103F0h
# 0h
# 8018000002000010h
# 0h
}
and COLLECT works for me!
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I doubt that any HP 50G will indicate that
A*X^2 + A*X + B*X + C = A*X^2 + (B+C)*X + C
as your message number 3 in this thread proposes. :-)
(unless A = C)
Edited: 17 Feb 2013, 4:38 p.m.
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He was talking about the typo: A*X^2 + (B+C)*X + C instead of A*X^2 + (A+B)*X + C.
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Good catch! Thank you Gerson I did miss type the expression. As you correctly pointed out it should have been A*X^2 + (A+B)*X + C and Mike I missed your subtle humor in post #4.
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I was wondering one more minor thing which doesn't really deserve its own thread. Is it possible in the equation editor, with an expression already entered, to add a factor or a summand on the beginning, from the left?
Ie. we have b•c. Is it possible to multiply it by a from the left, so we have a•b•c? Same question for b+c, so we get a+b+c?
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Hi,
On my HP-28S,
'A*x^2 + A*x + B*x + C' x 2 TAYLR returns 'C + (A+B)*x + A*2/2*x^2'
then a simple COLCT leads to '(A+B)*x + A*x^2 + C'
Is that expression close enough to the expected format?
Edited: 18 Feb 2013, 5:11 a.m.