IBM Support

PI73629: POTENTIAL UNDETECTED DATA CORRUPTION FOR ESSL DCFTD, DRCFTD, DCRFTD, SCFTD, SCRFTD, SRCFTD

 

APAR status

  • Closed as program error.

Error description

  • Error Description:
For some transform lengths, an application using at least one of
these ESSL FFT subroutines DCFTD, DRCFTD, DCRFTD, SCFTD, SCRFTD,
and SRCFTD may experience undetected data corruption (results
that are less accurate than expected) due to the phase factors
being computed using a single precision representation of the
transform length instead of a double precision representation of
the transform length.

USERS AFFECTED:
The application is not impacted if the FFT transform length S is
less than 8,388,608 or S can be represented as
              S = (2**i)(3**j)(5**k)(7**l)(11**m)(13**n) where
S>= 8,388,608 and S <= 2^30, and S, i, j, k, l, m, n satisfy all
of the following conditions:
           a) 0<=i<=30, 0<=j<=10, 0<=k, l, m, n<=5
           b) if i <9 and j<3: k+l+m+n<7
           c) if i<9 and j >=3: (j+1)/2 +k+l+m+n<7
           d) S is not equal to 665,127,936; 755,827,200;
786,060,288;  812,934,144; 846,526,464; 886,837,248;
967,458,816; 987,614,208; 993,586,176; 1,048,080,384

For all other transform lengths an application may be impacted.
Please contact IBM Support to confirm whether or not you are
impacted.

Local fix

  • 



Problem summary


    

  •  For some transform lengths, an application
using at least one of these ESSL FFT
subroutines DCFTD, DRCFTD, DCRFTD, SCFTD,
SCRFTD, and SRCFTD may experience undetected
data corruption (results that are less accurate
than expected) due to the phase factors being
computed using a single precision
representation of the transform length instead
of a double precision representation of the
transform length.

    



Problem conclusion


    

  •  Install the applicable fix as soon as it is
available.
PIxxxx - IBM ESSL 5.3.0.2 for AIX
PIxxxx - IBM ESSL 5.2.0.4 for AIX
PIxxxx - IBM ESSL 5.1.0.7 for AIX
PIxxxx - IBM ESSL for Linux on Power 5.4.0.1
PIxxxx - IBM ESSL for Linux on Power 5.3.2.1
PIxxxx - IBM ESSL for Linux on Power 5.2.0.4
PIxxxx - IBM ESSL for Linux on Power 5.1.1.3BG/Q

    



Temporary fix


    

  • 



Comments


    

  • 



APAR Information




    

  • APAR number
    PI73629
    • 

  • Reported component name
    ESSL LINUX V5.1
    • 

  • Reported component ID
    5765L51LP
    • 

  • Reported release
    520
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    YesHIPER
    • 

  • Submitted date
    2016-12-12
    • 

  • Closed date
    2016-12-12
    • 

  • Last modified date
    2016-12-12
    • 





    

  • APAR is sysrouted FROM one or more of the following:
    

    
PI73538
    

    • 

  • APAR is sysrouted TO one or more of the following:
    

    • 



Fix information


    

  • Fixed component name
    ESSL LINUX V5.1
    • 

  • Fixed component ID
    5765L51LP
    • 



Applicable component levels


    

  • R520  PSY
       UP
    • 








      
              
                            

              

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Document Information


            

            


                        

            Modified date:
            

            10 March 2021
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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