A detail in TMinuit MIGRAD call to FCN

From: Chris Jillings (chris@owl.phy.queensu.ca)
Date: Thu Oct 29 1998 - 04:51:01 MET


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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=                                                               =
= Chris Jillings                                                =
= Department of Physics   phone/voice mail: (613) 545-6000x4805 =   
= Queen's University      fax: (613) 545-6813                   =
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