Intel® oneAPI Math Kernel Library
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Question with df?EditPPSpline1D in Data Fitting Functions

Tianxiong_Lu
Beginner
315 Views

Hi all,

I have a question about parameter bc of function df?EditPPSpline1D.  In the documantation ( https://software.intel.com/en-us/node/522222#D69BA4E7-E8BD-4413-A2A9-769D5002F832 ) says :

bc

const float* for dfsEditPPSpline1D

const double* for dfdEditPPSpline1D

Pointer to boundary conditions. The size of the array is defined by the value of parameter bc_type:

  • If you set free-end or not-a-knot boundary conditions, pass the NULL pointer to this parameter.

  • If you combine boundary conditions at the endpoints of the interpolation interval, pass an array of two elements.

  • If you set a boundary condition for the default quadratic spline or a periodic condition for Hermite or the default cubic spline, pass an array of one element.

But if y is vector value function with dimension ny(>1), on the last case, it only need one element array? or ny elements array instead?

 

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Gennady_F_Intel
Moderator
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the owner of this code says - - it only need one element array

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Tianxiong_Lu
Beginner
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Thank you. But what value should be provided while y is vector value function with dimension ny(>1) ?

For example, the boundary condition type DF_BC_Q_VAL for default quadratic spline, the description in the documentation is "function value at point (x0+x1)/2", but function value is a vector with dimension ny. 

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VictoriyaS_F_Intel
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Hello Tianxiong Lu,

Intel® MKL Data Fitting routines restricts the length of the array bc to 1 for case ny > 1 and the boundary condition type is DF_BC_Q_VAL. If you need a different boundary condition for each coordinate of the vector function, please, construct spline for each coordinate separately.

Best regards,

Victoriya

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