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[Bug-gsl] [bug #52230] odeiv2/msadams fails with order change -2
From: |
Tuomo Keskitalo |
Subject: |
[Bug-gsl] [bug #52230] odeiv2/msadams fails with order change -2 |
Date: |
Sun, 15 Oct 2017 02:42:53 -0400 (EDT) |
User-agent: |
Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:56.0) Gecko/20100101 Firefox/56.0 |
URL:
<http://savannah.gnu.org/bugs/?52230>
Summary: odeiv2/msadams fails with order change -2
Project: GNU Scientific Library
Submitted by: tkeskita
Submitted on: Sun 15 Oct 2017 06:42:52 AM UTC
Category: Runtime error
Severity: 2 - Minor
Operating System: OSX
Status: In Progress
Assigned to: tkeskita
Open/Closed: Open
Release: 2.4
Discussion Lock: Any
_______________________________________________________
Details:
Subject: [Bug-gsl] msadams.c:973 aborts with GSL_ESANITY
Date: Tue, 26 Sep 2017 14:36:02 -0400
From: Michael Kaufman <address@hidden>
To: address@hidden
CC: Michael C. Kaufman <address@hidden>
Hi all,
since the header says that this is a sanity check that shouldn't happen, I
supposed I ought to report it.
-- order change -2
gsl: msadams.c:973: ERROR: msadams_apply too large order change
Default GSL error handler invoked.
I'm running on OSX 10.11.6 using a gsl-2.4_1 from macports.
I'm solving a 72 equation ODE.
The form of the equation is:
dA_m(z)/dz = -a_m*A_m(z)+Sum_n[K_mn(z)*A_n(z)*exp(j*b_mn*z)]
where I split the complex A_m's into real and imaginary parts.
Unfortunately, the exact functional form of K_mn(z) is rather complicated, so
there is no simple program (that I can write) that trips this bug.
This is how I initialize:
driver = gsl_odeiv2_driver_alloc_y_new(&sys, gsl_odeiv2_step_msadams,
0.05, abstol, 0);
Strangely, if I solve the ODE with and abstol of 1e-8 and then immediately
afterward solve again with an abstol of 1e-10, (for convergence testing) then
the abort happens (call this case 1). If I solve just one time with
abstol=1-10, then the abort doesn't happen (I'm reasonably sure that my
initial conditions are the same) -> call this case 2.
By the by, after turning the gsl_error_handler off, under case 1 the ODE
solver continues and delivers an answer that looks the same as case 2 to at
least 5 significant digits.
M
------
For continued discussion, see thread
https://lists.gnu.org/archive/html/bug-gsl/2017-09/msg00006.html
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