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[Lapack] Using different version get different results

Dear Authors:
I compiled Lapack3.0, 3.1.1, 3.2.1 using the machine, the compiler and compiler 
options as below:
system: Red Hat Enterprise Linux AS release 4 (Nahant Update 3) 
CPU: Intel(R) Xeon(R) CPU  5110  @ 1.60GHz 
compiler: intel visual fortran 11.1.072
OPTS: -O2 -xSSE3 -static-intel -msse3
NOOPT = -O0


I have trouble when I use different versions of Lapack to calculate the same 
issue. I compared the results of the programs, compiling with Lapack 3.0,  
3.1.1,  and  3.2.1.  Furthermore, I performed the same test with Intel MKL. 

After compared these different versions, Lapack 3.0 seems more stable than the 
other versions, and I think it is possible that I encountered some bug in 
Lapack 3.1.1 and 3.2.1.

The compiling info and output results are below (they all have the same input 
data): 

ifort -O3 -xSSSE3 -static-intel -mssse3   -o scat PublicDataType.o 
InitialPubicData.o TrapInFirstBZ.o SomeInitialFunction.o DielectricFunction.o 
MainSubroutine.o MatrixINVandEIG.o BuildAndSloveMatrix.o ImportantMatrixs.o 
CalculateEnergyFlux.o Emission.o ReflectAndTrans.o TotalEmission.o Main.o  
-lmkl_intel_lp64 -lmkl_core -lpthread -lmkl_sequential
now up2dated!
[wangxh6 at c0124 del]$ ./scat
 Data from sides(upper/lower):BOTH;
 And incident from: UPPER;
 Calculate with:  "REAL"
  -11.6188765665993       -10.6188765768530     
  0.999999989746327  
 
ifort -O3 -xSSSE3 -static-intel -mssse3   -o scat PublicDataType.o 
InitialPubicData.o TrapInFirstBZ.o SomeInitialFunction.o DielectricFunction.o 
MainSubroutine.o MatrixINVandEIG.o BuildAndSloveMatrix.o ImportantMatrixs.o 
CalculateEnergyFlux.o Emission.o ReflectAndTrans.o TotalEmission.o Main.o  
-L/export/home/wangxh6/lapack/3.0 -llapack -lblas
now up2dated!
[wangxh6 at c0124 del]$ ./scat
 Data from sides(upper/lower):BOTH;
 And incident from: UPPER;
 Calculate with:  "REAL"
 -0.141758274548027       0.858241725451776     
  0.999999999999803    
 
ifort -O3 -xSSSE3 -static-intel -mssse3   -o scat PublicDataType.o 
InitialPubicData.o TrapInFirstBZ.o SomeInitialFunction.o DielectricFunction.o 
MainSubroutine.o MatrixINVandEIG.o BuildAndSloveMatrix.o ImportantMatrixs.o 
CalculateEnergyFlux.o Emission.o ReflectAndTrans.o TotalEmission.o Main.o  
-L/export/home/wangxh6/lapack/3.2.1 -llapack -lblas
now up2dated!
[wangxh6 at c0124 del]$ ./scat
 Data from sides(upper/lower):BOTH;
 And incident from: UPPER;
 Calculate with:  "REAL"
  -11.6188761788806       -10.6188761520427     
   1.00000002683791  
 
ifort -O3 -xSSSE3 -static-intel -mssse3   -o scat PublicDataType.o 
InitialPubicData.o TrapInFirstBZ.o SomeInitialFunction.o DielectricFunction.o 
MainSubroutine.o MatrixINVandEIG.o BuildAndSloveMatrix.o ImportantMatrixs.o 
CalculateEnergyFlux.o Emission.o ReflectAndTrans.o TotalEmission.o Main.o  
-L/export/home/wangxh6/lapack/3.1.1 -llapack -lblas
now up2dated!
[wangxh6 at c0124 del]$ ./scat
 Data from sides(upper/lower):BOTH;
 And incident from: UPPER;
 Calculate with:  "REAL"
  -11.6188764610851       -10.6188764766732     
  0.999999984411938  

For some reason, the first two numbers of each group must be between -1 and 1. 
Only the second group is rational.
 
Using these compiled programs to compute other input data, some results end up 
the same but some do not. I do not have the experience to track down the cause 
(perhaps it is a bug). I could provide my code if anyone could give me a help. 
Thanks in advance.

Sincerely yours,
Hao xiang jiang
2010-05-21 



jhaox 
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