unxpected Pawley error

babaryk

Dear TOPAS users,

TOPAS (BAXS, v.4.2) produces error during an attempt of simple Pawley decomposition:

r_exp 0 r_exp_dash 0 r_wp 0 r_wp_dash 0 r_p 0 r_p_dash 0 weighted_Durbin_Watson 0 gof 0
iters 1000
do_errors
xdd ".\c.xye" xye_format
r_exp 1.238 r_exp_dash 2.244 r_wp 2.945 r_wp_dash 5.339 r_p 2.198 r_p_dash 4.583 weighted_Durbin_Watson 0.298 gof 2.379
bkg @ 0 0 0 0
One_on_X(@, 200)
LP_Factor( 90)
neutron_data
Specimen_Displacement(@, -0.26944)
Simple_Axial_Model( 21.16726)
lam
ymin_on_ymax 0.001
la 1 lo 1.594 lh 0.5
x_calculation_step 0.05
hkl_Is
TCHZ_Peak_Type(, 0.04575,, -0.14971,, 0.18457,, 0.0001,, 0.00012,, 0.07305)
r_bragg 0
phase_name "a"
space_group "P21212"
a @ 19.000
b @ 14.000
c @ 5.000

Non-linear least squares (c) 1992-2007 Alan A. Coelho
Loading xyz's for P21212 from file C:\TOPAS4-2\sg\p21212.sg
Space group P21212 is not centrosymmetric
Number of equivalent positions 4
Number of hkls generated for C:\TOPAS4-2\sg\p21212.sg 1793
Number of independent parameters : 1802
Number of independent parameters : 1802

What could be an issue?

Thank you.
Artem

rowlesmr

What is the error?

.

as an aside, I see you have neutron_data in there, as well was Specimen_Displacement(@, -0.26944).

Was your neutron data collected in bragg-bentano geometry? If not, the specimen displacement macro is going to be wrong.

babaryk

Dear Matthew,

What is the error?

'Exception caught'

as an aside, I see you have neutron_data in there, as well was Specimen_Displacement(@, -0.26944).

Was your neutron data collected in bragg-bentano geometry? If not, the specimen displacement macro is going to be wrong.

Indeed, 'Specimen_Displacement' macro is used incorrectly, you have noticed, it is a leftover from the template file.
Applicable 'Zero_Error' for the case, however, does not resolve some numerical problems (?).

Regards,
Artem

alancoelho

Artem

You need to trouble shoot the problem; remove items until it works; then slowly introduce items until you have identified what the problem is.

Once you have done that and you are still in trouble then send me a simplified version of your INP and data file and I will have a look.
cheers
alan

babaryk

Dear Alan, Matthew,

Thank you for the response.

The issue has been found.

I've not believed the problem came form a set of tags I used eventually after
comparison of the input file with any other one of minimal TOPAS input for Pawley fitting.
And it is pretty much similar as supposed to.
Consequently, the first clue was to check data consistency.
While I have used the same formatted data before, it was seemed above suspicion.
But, a detector range was integrated starting from 0.000 point in the file, and for the
first run I have used the entire range leading to the error.
Omitting the point, the run has been done in a usual way.

Thus, I guess something wrong was going to be with 'x_calculation_step'.

Could you comment a bit what math problem has been occured?

Thank you.
Artem

alancoelho

Hi Artem

I don't what what the math problem was due to the erroneous data file; indeed I don't want to know.

There are at least 1000 error messages but it is no exhaustive. More checking could be put in but it would come at the cost of program speed. For example no checking is performed in regards to numeric errors such as Ln or sqrt of negative numbers.

With a little familiarity it should be possible to trouble shoot problems in a speedy manner. And the only way to get familiar is to have the odd error.

Cheers
Alan