DAE initial value problem:
user defined problem

Please specify the dimension of the vector y here
n =   Important: 1 <= n <= 10!

Please write here the piece of code which computes the functions G1,...,Gn
which make up the implicit ode G(t,y,y')=0, G= (G1,...,Gn)T. They must have the mathematical structure Gi = Gi(t,y(1),...,y(n),yp(1),...,yp(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 must not use as label the number 1 and any number >= 90000 There is a variable ires: if the current values of t,y or yp do not allow the evaluation of one of the G(i), then set ires=-1 and return. The code then will try smaller stepsizes in order to avoid a repetition of this.

Specify the integration interval:
t0 =
tend =

Specify the initial values for y and yp
This is a list of 2*n numbers, separated by blank or comma, in the meaning y(1), yp(1),....,y(n),yp(n). These should be consistent, that means they should satisfy the implicit equations a t0. The code however will try to correct them if this is not the case. However this may fail.

These values should be considered as consistent:
yes
no

Select two components of y for plotting: index1=index2=1 is allowed
index1 = Important index1 from 1,...,n !
index2 = Important: index2 from 1,...,n !

How should the error criterion be applied?
uniform tolrel =
smally=   Then atol=tolrel × smally
individual specify the parameters rtol(i), atol(i) here as a list of 2n numbers

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

Please select the initial stepsize hstart:
hstart = Important: 0 < hstart <= hmax !

Please specify the maximal order allowed:
maxorder=
Important: 1 <= maxorder <= 5

Should the algebraic components be included in the precision test?
yes
no

Here you must define the status of the y-variables in the corresponding field: a list of n numbers 1 or -1. -1 means purely algebraic
y-status =

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.

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28.09.2011