unexpected mkl_interval addition result

unexpected mkl_interval addition result


The attached simple program "ti.f90" gives

1 =[1.00000000000000000,1.00000000000000000] 0.00E+00 -> GOOD
3 =[3.00000000000000000,3.00000000000000000] 0.00E+00 -> GOOD
1/3 =[0.33333333333333331,0.33333333333333337] 0.56E-16 -> GOOD
4/3 =[1.33333333333333326,1.33333333333333348] 0.22E-15 -> GOOD
1+1/3=[1.33333333333333348,1.33333333333333348] 0.00E+00 -> BAD !

The compilation was done using

ifort -D_LINUX $R/include/mkl_interval.f90 ti.f90
-L$R/lib/32 -lmkl_lapack -lmkl_ia32

Is it a mkl/8.0.1/lib/32/libmkl_lapack.a library bug or
I'm wrong (I have not find any detailed documentation)
Best regards


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For more complete information about compiler optimizations, see our Optimization Notice.

Yes, this is a bug. Thank you for pointing it out.

We are currently working on this, and, hopefully,the stuation will be fixed in MKL 8.1.

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