Please write here the piece of code which computes the functions f₁,...,f_n
which make up the right hand side of the ode y' = f(t,y), f = (f₁,...,f_n)^T. They must have the structure f_i = f_i(t,y(1),...,y(n)). You must obey the FORTRAN conventions.
You might use here variables i,j,k (e.g. for loops or counting), the logicals bool1, bool2 , bool3, a vector of 100 components v(.) , the variables h1,h2,h3,h4 (e.g. for intermediate calculations) which all are initialized with zero resp. false and the constants pi, e, sqrt2 (with their mathematical meaning).
you also can use the dimension of y which is here the variable nf
f(1)=-4.d0*y(1)+y(1)*y(2)*0.1d0+3.d0*y(2) f(2)=1.d0*y(1)-2.d0*y(2)-0.1d0*y(1)*y(2)+0.1d0

Specify the integration interval:

t0    =
tend =

Specify the initial values for y
This is a list of n numbers, separated by blank or comma.
1.0, -4.0

Select two components of y for plotting: index1=index2=1 is allowed

index1 =		Important index1 from 1,...,n !
index2 =		Important: index2 from 1,...,n !

please specify the relative precision you want to obtain
tol     =
please specify a typical value for ''small'' function values to be replaced by this parameter smally in the relative error criterion:
smally=

Please select the maximum allowed stepsize hmax:
hmax  = Important: 0 < hmax < (t_end-t₀)/2 !

Please specify the number of subintervals of equal length, which must be processed separately:
1 <= num <= 100. 1 means there are no fixed intermediate grid points (recommended).

Warning!!! - This may take some time.

Click on "evaluate", in order to submit your input.

back to the theory page