TPCFastTransformation: Resolve recursion at compile time with templates.

[fweig]

No description provided.

[github-actions]

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[davidrohr]

Looks good to me, just one comment. You can also already mark it as ready to run the CI.

[alibuild]

Error while checking build/O2/fullCI_slc9 for 2525d2d at 2025-07-02 17:11:

## sw/BUILD/O2-latest/log
/sw/SOURCES/O2/14462-slc9_x86-64/0/GPU/TPCFastTransformation/NDPiecewisePolynomials.inc:168:111: error: no matching function for call to 'o2::gpu::MultivariatePolynomialParametersHelper::getNParameters(unsigned int, unsigned int, bool)'
/sw/SOURCES/O2/14462-slc9_x86-64/0/GPU/TPCFastTransformation/NDPiecewisePolynomials.inc:219:112: error: no matching function for call to 'o2::gpu::MultivariatePolynomialParametersHelper::getNParameters(unsigned int, unsigned int, bool)'
/sw/SOURCES/O2/14462-slc9_x86-64/0/GPU/TPCFastTransformation/MultivariatePolynomial.h:59:59: error: no matching function for call to 'o2::gpu::MultivariatePolynomial<5, 4>::getNParameters(unsigned int, unsigned int, bool)'
/sw/SOURCES/O2/14462-slc9_x86-64/0/GPU/TPCFastTransformation/MultivariatePolynomial.h:59:30: error: cannot convert '<brace-enclosed initializer list>' to 'uint32_t' {aka 'unsigned int'} in initialization
/sw/SOURCES/O2/14462-slc9_x86-64/0/GPU/TPCFastTransformation/MultivariatePolynomial.h:52:218: error: no matching function for call to 'o2::gpu::MultivariatePolynomial<0, 0>::getNParameters(const uint32_t&, const uint32_t&, const bool&)'
/sw/SOURCES/O2/14462-slc9_x86-64/0/GPU/TPCFastTransformation/MultivariatePolynomial.h:52:189: error: cannot convert '<brace-enclosed initializer list>' to 'uint32_t' {aka 'unsigned int'} in initialization
/sw/SOURCES/O2/14462-slc9_x86-64/0/GPU/TPCFastTransformation/MultivariatePolynomial.h:59:59: error: no matching function for call to 'o2::gpu::MultivariatePolynomial<5, 5, true>::getNParameters(unsigned int, unsigned int, bool)'
/sw/SOURCES/O2/14462-slc9_x86-64/0/GPU/TPCFastTransformation/MultivariatePolynomial.h:59:30: error: cannot convert '<brace-enclosed initializer list>' to 'uint32_t' {aka 'unsigned int'} in initialization
ninja: build stopped: subcommand failed.

Full log here.

[alibuild]

Error while checking build/O2/fullCI_slc9 for 97c2b94 at 2025-07-15 11:17:

No log files found

Full log here.

[sgorbuno]

i have no objections