[SciPy-user] problem with odeint

Ryan Krauss ryanlists at gmail.com
Thu Mar 2 16:32:05 CST 2006


I am having a problem with odeint.  My integration runs o.k. if I
choose a fairly short time interval, but when I set the maximum value
for my t vector higher than about 1 second, I get this message:

In [178]: run sweptsine_ode.py
 lsoda--  at t (=r1), too much accuracy requested
       for precision of machine..  see tolsf (=r2) ls
      in above,  r1 =  0.5448183650273E+00   r2 =                  NAN
Excess accuracy requested (tolerances too small).
Run with full_output = 1 to get quantitative information.

Running with fulloutput produces:
{'hu': array([ 0.00020682,  0.00043534,  0.00043534, ...,  0.        ,
        0.        ,  0.        ]),
 'imxer': -1267232872,
 'leniw': 23,
 'lenrw': 68,
 'message': 'Excess accuracy requested (tolerances too small).',
 'mused': array([1, 1, 1, ..., 0, 0, 0]),
 'nfe': array([19, 27, 31, ...,  0,  0,  0]),
 'nje': array([0, 0, 0, ..., 0, 0, 0]),
 'nqu': array([2, 3, 3, ..., 0, 0, 0]),
 'nst': array([ 9, 13, 15, ...,  0,  0,  0]),
 'tcur': array([ 0.00106956,  0.00235387,  0.00322454, ...,  0.        ,
        0.        ,  0.        ]),
 'tolsf': array([  7.88983883e-314,   7.88983883e-314,   7.88983883e-314, ...,
         0.00000000e+000,   0.00000000e+000,   0.00000000e+000]),
 'tsw': array([ 0.,  0.,  0., ...,  0.,  0.,  0.])}

The script is attached and should be self contained.  Messing with
atol and rtol doesn't seem to help, so I don't know what the message
about requested accuracy means.

Any help/direction in fixing this would be appreciated.

Thanks,

Ryan
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