Intel® oneAPI Math Kernel Library
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## DataFitting bug ? Beginner
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Pls run the program bellow,and confirm the difference between NY==1 and NY==2 case.

// int NY = 2;
int NY = 1;
double x[] = {1,2, 3, 4,  5};
double y[] = {0,2,-1,-0.5,0,-1,1,-2,-1.5,-1};
int    NX  = sizeof(x)/sizeof(x);
int order  = 1;
int dorder[] = { 0,0 };
int ndorder = sizeof(dorder)/sizeof(dorder);
double coef;
double xv   = 0.0;
double yv;
int status;
status = dfdEditPPSpline1D(task, DF_PP_LINEAR, DF_PP_DEFAULT, DF_NO_BC , NULL, DF_NO_IC, NULL, coef, DF_NO_HINT);
status = dfdConstruct1D( task, DF_PP_SPLINE, DF_METHOD_STD );
for(int i=1;i<=NX;++i)
{
xv = i;
status = dfdInterpolate1D( task, DF_INTERP, DF_METHOD_PP, 1, &xv, DF_NON_UNIFORM_PARTITION, ndorder, dorder, NULL, yv, DF_MATRIX_STORAGE_ROWS, NULL );
if(NY==2) printf("status = %d x=%g y=[%g,%g]\n",status,xv,yv,yv);
else      printf("status = %d x=%g y=[%g]\n",status,xv,yv);
}

===== the results when NY=1 follow
status = 0 x=1 y=
status = 0 x=2 y=[-1.5]    <= why not 2.0 ?
status = 0 x=3 y=[-1]
status = 0 x=4 y=[-0.5]
status = 0 x=5 y=

===== the results when NY=2 follow
status = 0 x=1 y=[0,-1]
status = 0 x=2 y=[2,1]   <= Yes OK!
status = 0 x=3 y=[-1,-2]
status = 0 x=4 y=[-0.5,-1.5]
status = 0 x=5 y=[0,-1]
------------------------------------------------
I got the results under  MKL V11.1.1 Product Build 20131010 for 32-bit application on Windows-7.

8 Replies Moderator
114 Views

thanks, we will check this case. Moderator
114 Views

yes, it looks a bug. the issue is escalated. we will update this thread in the case any news. Employee
114 Views

Hello Shigeo Kobayashi,

The test case you have provided reproduces a bug in MKL 11.1.1. dfdinterpolate1D function has an issue with processing small tasks when ny = 1 and nsite = 1, like in your example.

This issue was also revealed by our internal testing and the fix is planned for the next MKL 11.1 update. Currently you could use a workaround: Please use nsite = 2 and pass array of 2 elements as an array of interpolation sites to obtain correct results. Beginner
114 Views

Hi Victoriya,
Thank you for your comment. Yes,I wait for the next MKL release(this month?). Moderator
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yes Moderator
114 Views

Shigeo,

the fix of the problem you can find into 11.1 update2 released yesterday. Would you please check the issue with this update and let us know the results. Beginner
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