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rkqc_stepper(numer) Numerical Analysis rkqc_stepper(numer)

NAME

rkqc_stepper - Object that performs one step of Runge_Kutta method and does it with accuracy testing.

DESCRIPTION

Fifth order Runge_Kutta step with monitoring of local truncation error to ensure accuracy and adjust stepsize. Input are function that computes the right side of the system of ordinary equations (derivatives) and the starting value of independent variable time. Also input is the stepsize to be attempted guess_step and the required accuracy eps. See Numerical Recipes in C, by W.H.Press, et all, Cambridge University Press, 1988, p. 577. In most cases its subclass rkqc_solver should be used in applications.

SUPERCLASS

rk4_stepper

INSTANCE VARIABLES

time is the time of the initial state of the system.

t_save is the variable used for saving time. This variable is private.

guess_step is the suggested stepsize.

next_step is the estimated next step.

step_made is the stepsize that was actually accomplished.

eps is the accuracy of solution.

scale is the scale against which the error is scaled.

x_save is the array for temporary storing state of the system. It is private variable.

x_temp is the array for temporary storing state of the system. It is private variable.

MESSAGES

eps=argument sets the value of the instance variable eps.

eps? returns the value of eps.

guess_step=argument sets the value of the instance variable guess_step.

guess_step? returns the value of guess_step.

next_step? returns the value of next_step.

step_made? returns the value of step_made.

time=argument sets the value of the instance variable time.

time? returns the value of time.

tick! Computes the solution of the system for the time = time + step_made.

EXAMPLES

See example in rkqc_solver