NDP or Arithmetic Errors

Note: Since GEMPACK Release 10, arithmetical errors (eg, square roots of negative numbers) are reported in a way that lets you usually pinpoint the cause. Previously, this was not the case. The advice below applies mainly to previous GEMPACK releases.

What to do if an NDP Error occurs?

These may occur while you are carrying out a simulation. An NDP error is usually an overflow error which usually indicates that some endogenous variable has become enormous (say more than 10 raised to the power 20).

This most likely indicates a closure which is not really valid. Alternatively, it can happen in a multi-step calculation if a variable which should have been declared as a
Variable (Change)
has been declared as a percentage change variable.

To find the variables which have become enormous, try to carry out a 1-step (that is, Johansen) simulation and use GEMPIE to produce a Print file. Then search in the Print file for "E+" since that is used to indicate large powers of 10.

Alternatively, if the problem only occurs when you extrapolate, try to get an Extrapolation Accuracy file for a small number of steps (say, 1,2,4) and then search in it for "E+". [Put the statement "extrapolation accuracy file = yes ;" in your Command file to produce an Extrapolation Accuracy file.]

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