A detail in TMinuit MIGRAD call to FCN

Chris Jillings (chris@owl.phy.queensu.ca)
Wed, 28 Oct 1998 22:51:01 -0500 (EST)

Hello,
This point is a fine detail, but it may be important to me.
>From reading Fred James'reference manual for version 94.1 of Minuit, I
find on page 9 a list of iflag values used in the call to FCN. It has I
flag = 1,2, and 3 (see page 9). It seems that FCN is called with iflag=1
for startup. So I test on iflag, as in the example, and so some
initialization there.

But when I run TMinuit, I get the following output (having sent print
level to 3.)
**********
** 4 **MIGRAD 500 1
**********
FIRST CALL TO USER FUNCTION AT NEW START POINT, WITH IFLAG=4.
START MIGRAD MINIMIZATION. STRATEGY 1. CONVERGENCE WHEN EDM .LT.
1.00e-03
FCN=-0.519027 FROM MIGRAD STATUS=INITIATE 21 CALLS 22
TOTAL

What does IFLAG=4 mean? "First call to use function" suggests to me that I
should test on iflag==4 to do my initializations.

Thank you for any help.

Chris

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