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Desolve gives wrong results
12-24-2019, 06:21 AM
Post: #5
Stevetuc Offline
Senior Member
 		Posts: 313
Joined: Jan 2014
RE: Desolve gives wrong results
(12-23-2019 06:47 PM)CyberAngel Wrote:  
(12-23-2019 03:25 PM)COB160 Wrote:  Goodafternoon everybody,
I am dealing with desolve HP prime function, in particular if I type desolve(y'=-x/y,y) i get two wrong results, wich are: sqrt(-2*G_0-x^2 ) and -sqrt(-2*G_0-X^2). In fact the correct result should be, according to wolframalpha: sqrt(-x^2+c) and -sqrt(-x^2+c). Does the difference depend on the interpretation of G_0 or c constant? Otherwise the result is incorrect with respect of the sign.
Thank in advance for your help

The constant(s) could be anything
thus the answers are all correct.

Correct but unfriendly, as the constant could be simplified to c_1 say, even if c is reserved.
Its fortunate indeed that the OP didnt require the answer to
desolve(y'=-i*x/y,y)
Wolfram gives this as
y(x) = -sqrt(c_1 - i*x^2) and y(x) = sqrt(c_1 - i*x^2)

Prime with Simplify:Maximum gives the undeniably spectacular
Code:
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[.....]

I had to truncate the result as its longer than the forum can handle!
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Messages In This Thread
Desolve gives wrong results - COB160 - 12-23-2019, 03:25 PM
RE: Desolve gives wrong results - COB160 - 12-23-2019, 07:28 PM
RE: Desolve gives wrong results - Stevetuc - 12-24-2019 06:21 AM
RE: Desolve gives wrong results - Stevetuc - 12-24-2019, 03:53 PM
RE: Desolve gives wrong results - Stevetuc - 12-24-2019, 04:55 PM
RE: Desolve gives wrong results - COB160 - 12-24-2019, 08:17 AM
RE: Desolve gives wrong results - COB160 - 12-24-2019, 08:25 AM
RE: Desolve gives wrong results - Aries - 12-25-2019, 09:13 AM
RE: Desolve gives wrong results - parisse - 12-24-2019, 06:54 PM
RE: Desolve gives wrong results - Stevetuc - 12-24-2019, 09:43 PM
RE: Desolve gives wrong results - parisse - 12-25-2019, 04:39 PM
RE: Desolve gives wrong results - Stevetuc - 12-25-2019, 06:25 PM
RE: Desolve gives wrong results - Marcel - 12-25-2019, 02:15 PM
RE: Desolve gives wrong results - lrdheat - 12-25-2019, 05:29 PM



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