[Bug-gsl] gsl_odeiv_evolve_apply can only decrease step size, not increase

[Chris Rogers]

I am using gsl v1.15

I note that ODE evolver, gsl_odeiv_evolve_apply, defined in 
gsl-1.15/ode-initval/evolve.c, can only decrease the step size in the 
integration. If I define a control function that results in an 
increasing step size, the evolver does not increase the step size.

For example, if the integration goes from a region where the derivative 
changes quickly to one where the derivative changes slowly, the step 
size should get larger. This is not possible, even if a control function 
is defined that yields a large step size.

Reviewing the source code, there is a code block like

    if (hadjust_status == GSL_ODEIV_HADJ_DEC) {
        <some stuff>
    }

but no code block like

    if (hadjust_status == GSL_ODEIV_HADJ_INC) {
        <some other stuff>
    }

Let me know if I can help in any way resolve the issue.

Regards,
Chris Rogers


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