Equation can't solve with 2.15 but 2.10 can
03-18-2021, 08:03 AM (This post was last modified: 03-20-2021 02:37 AM by Gene.)
Post: #1
 BINUBALL Member Posts: 133 Joined: Mar 2021
Equation can't solve with 2.15 but 2.10 can
I have the equation that cannot solve in 50g with rom version 2.15.
x^2+x*y=10 and y+3*x*y^2=57.
In rom 2.15 When I tried solve this equation. It gives "Unable to factor" in exact mode, "Not exact system" in approx mode. You might think it's a normal case up to here, but In EMU48 with rom 2.10 CAN SOLVE IT!. It demands change mode to approx. and gives answer.
Why 50g with rom version 2.15 cannot solve it?

S.Korean / HP-50G | fx-570EX | fx-570CW | HP-200LX
03-18-2021, 11:33 AM
Post: #2
 peacecalc Member Posts: 187 Joined: Dec 2013
RE: Eqaution can't solve with 2.15 but 2.10 can
Hello PINUBALL,

try:

stack (3): [ 'x^2+x*y=10' 'y+3*x*y^2=57']
stack (2): ['X' 'Y']
stack (1): [1 1] initial guess

and use command MSLV, you get [2.000 3.000].
03-18-2021, 11:46 PM
Post: #3
 BINUBALL Member Posts: 133 Joined: Mar 2021
RE: Eqaution can't solve with 2.15 but 2.10 can
(03-18-2021 11:33 AM)peacecalc Wrote:  Hello PINUBALL,

try:

stack (3): [ 'x^2+x*y=10' 'y+3*x*y^2=57']
stack (2): ['X' 'Y']
stack (1): [1 1] initial guess

and use command MSLV, you get [2.000 3.000].
I know that method, but I want to get all 4 roots. Because EMU48 gives 4 roots.

S.Korean / HP-50G | fx-570EX | fx-570CW | HP-200LX
03-19-2021, 11:58 PM
Post: #4
 franz.b Member Posts: 140 Joined: Jan 2017
RE: Eqaution can't solve with 2.15 but 2.10 can
what is the exact procedure you use to solve? I have a 50g with firmware 2.15 and one with 2.08. If you want I can do some tests.

Hardware: Hp48S - Hp50g (5x black + 1 blue) - HP39gII - Hp27s - Casio fx-CG50
03-20-2021, 02:10 AM
Post: #5
 BINUBALL Member Posts: 133 Joined: Mar 2021
RE: Eqaution can't solve with 2.15 but 2.10 can
(03-19-2021 11:58 PM)franz.b Wrote:  what is the exact procedure you use to solve? I have a 50g with firmware 2.15 and one with 2.08. If you want I can do some tests.
stack (2): [ 'x^2+x*y=10' 'y+3*x*y^2=57']
stack (1): ['X' 'Y']
Mode is exact, complex. Thus Header will be C=. And execute SOLVE. In my emu48, It ask change mode to approx and gives four answer. 2.15 return Unable to factor.
Here is picture of my emu48 gives four roots.

S.Korean / HP-50G | fx-570EX | fx-570CW | HP-200LX
03-20-2021, 10:05 AM
Post: #6
 franz.b Member Posts: 140 Joined: Jan 2017
RE: Equation can't solve with 2.15 but 2.10 can
with both calculators the result is "Unable to factor".
For example, are you sure that all other system flags are set the same way?

Hardware: Hp48S - Hp50g (5x black + 1 blue) - HP39gII - Hp27s - Casio fx-CG50
03-20-2021, 10:58 AM
Post: #7
 BINUBALL Member Posts: 133 Joined: Mar 2021
RE: Equation can't solve with 2.15 but 2.10 can
(03-20-2021 10:05 AM)franz.b Wrote:  with both calculators the result is "Unable to factor".
For example, are you sure that all other system flags are set the same way?
I moved EMU48's flag setting to real 50G and that eq gives four roots. After flag compare, I figured it out. Answer is -109 SF. If -109 is set, numeric factorization is allowed.
I think after SF 109, most "Unable to factor" problem can solved.

S.Korean / HP-50G | fx-570EX | fx-570CW | HP-200LX
03-20-2021, 11:06 AM
Post: #8
 peacecalc Member Posts: 187 Joined: Dec 2013
RE: Equation can't solve with 2.15 but 2.10 can
Hello all,

I tried it, too. Yes, with flap 109 it works! Again, learned something new about that crazy machine, called hp 50g! Thank you all!
03-20-2021, 12:56 PM
Post: #9
 franz.b Member Posts: 140 Joined: Jan 2017
RE: Equation can't solve with 2.15 but 2.10 can
With the flag setting it works on both my versions, 2.08 and 2.15.

Hardware: Hp48S - Hp50g (5x black + 1 blue) - HP39gII - Hp27s - Casio fx-CG50
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