Hi experts,
I am trying to fit exponential function with my dataset(using RooDecay) . The fit Status Converges but the NOT POSDEF . I dont find any idea to fix this. The error is shown below.
EIGENVALUES OF SECOND-DERIVATIVE MATRIX:
-1.1216e-03 7.8769e-01 1.0749e+00 2.1385e+00
MINUIT WARNING IN HESSE
============== MATRIX FORCED POS-DEF BY ADDING 0.003260 TO DIAGONAL.
FCN=538269 FROM HESSE STATUS=NOT POSDEF 23 CALLS 156 TOTAL
EDM=1.77229e-05 STRATEGY= 1 ERR MATRIX NOT POS-DEF
EXT PARAMETER APPROXIMATE INTERNAL INTERNAL
NO. NAME VALUE ERROR STEP SIZE VALUE
1 dt 8.92747e-02 1.56443e-02 2.60157e-05 -1.38154e+00
2 mean 3.77404e-01 6.60677e-02 4.49178e-05 -1.17977e+00
3 sigma 2.74317e-01 4.83087e-02 2.93141e-04 -2.67330e+00
4 t 1.53458e+00 2.63378e-03 2.99858e-04 5.47741e-02
ERR DEF= 0.5
EXTERNAL ERROR MATRIX. NDIM= 25 NPAR= 4 ERR DEF=0.5
2.448e-04 -1.031e-03 7.471e-04 -5.937e-07
-1.031e-03 4.367e-03 -3.170e-03 -1.911e-07
7.471e-04 -3.170e-03 2.343e-03 1.180e-06
-5.937e-07 -1.911e-07 1.180e-06 6.937e-06
ERR MATRIX NOT POS-DEF
PARAMETER CORRELATION COEFFICIENTS
NO. GLOBAL 1 2 3 4
1 0.99703 1.000 -0.997 0.987 -0.014
2 0.99796 -0.997 1.000 -0.991 -0.001
3 0.99113 0.987 -0.991 1.000 0.009
4 0.19942 -0.014 -0.001 0.009 1.000
ERR MATRIX NOT POS-DEF
Can any body help me please?
Thank you
Cp