Need help writing DMIG in correct format using pyNastran

[empennage]

pyNastran version: 1.0.0

python version: 2.7.11

NX Nastran v10.2

Windows 7 64-bit

I want to use pyNastran to write a DMIG stiffness matrix for NX Nastran. However, I am getting the following Fatal error message:

*** USER FATAL MESSAGE 316 (IFPDRV)
     ILLEGAL DATA ON BULK DATA ENTRY DMIG   
     User information:
     See Bulk Data entry description in Section 5 of the NX NASTRAN
     Quick Reference Guide. If you are using the large field format make
     sure the number of entries is even.
 DMIG        KAAX       1       1               1       110635.31        

I have attached the Nastran files that replicate the fatal error message. The correctly formatted file is matrix_spring.dat with spring.pch as an include file DMIG. And, the fatal run is matrix_spring_pynastran.dat.

from pyNastran.bdf.bdf import BDF

# Create BDF object in pyNastran
model = BDF()
model.read_bdf('matrix_spring.dat')
dmig = model.dmigs.copy()
export = BDF()

# Export DMIG entries
export.add_dmig('KAAX', dmig['KAAX'].ifo, dmig['KAAX'].tin, dmig['KAAX'].tout,
                dmig['KAAX'].polar, dmig['KAAX'].ncols, dmig['KAAX'].GCj, dmig['KAAX'].GCi,
                dmig['KAAX'].Real, Complex=None, comment='Export DMIG Matrix')

export.write_bdf('dmig.bdf')

Let me know if you need any additional information.

[Steven Doyle]

Your data is formatted incorrectly.  Per the QRG:

The header entry containing IFO, TIN and TOUT is required. Each nonnull

column is started with a GJ, CJ pair. The entries for each row of that column

follows. Only nonzero terms need be entered. The terms may be input in

arbitrary order. A GJ, CJ pair may be entered more than once, but input of

an element of the matrix more than once will produce a fatal message.

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[Steven Doyle]

Nevermind...I think I read the table wrong.

You requested that the data be in double precision (TIN=2), but you output the data in single precision (TIN=1).  You need to either update TIN to be 1 or change your write statement to be:

    export.write_bdf('dmig.bdf', size=16, is_double=True)

The code should probably be updated to just ignore the write_bdf flags for matrices.  Nastran is a bit complicated :)

[empennage]

Thanks, that worked! I'm very grateful for your quick response.

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