Troubleshooting and Common Errors

gsl_sf_bessel_J0 or gsl_sf_bessel_Jn Undefined at Link Time

Cause:

GSL libraries were not linked after the object files, gsl-config is not on PATH, or the GSL include/library directories are not discoverable.

Fix:

Use the current Makefile and either expose gsl-config or pass GSL paths explicitly:

make clean
make PYTHON=python3 GSL_INCLUDE=/usr/include \
     GSL_LIB=/usr/lib/x86_64-linux-gnu all

python: command not found

Cause:

The Makefile default uses PYTHON ?= python. Some systems only provide python3.

Fix:

Pass PYTHON=python3 to make.

No module named Cython

Cause:

The wrapper build imports Cython from setup.py.

Fix:

Install Python build dependencies before running make all:

python3 -m pip install --user numpy Cython scipy

Undefined SetNumberThreads or get_nthreads Symbols

Cause:

Older builds did not compile the thread-control and PXD helper symbols required by the Cython wrapper.

Fix:

Rebuild from a checkout containing the current fixes:

make clean
make PYTHON=python3 all

wlcovpy requires ADDONSON=1, CLASSLIBON=1, PXDON=1

Cause:

setup.py generates python/cwlcovpy.pxd from the active addon settings. The current wrapper expects ADDONSON, CLASSLIBON, and PXDON to be enabled.

Fix:

Keep ADDONSON = 1 in Makefile_settings and CLASSLIBON = 1 in addons/Makefile_addons_settings. PXDON is enabled automatically when CLASSLIBON is on.

ABI Mismatch During Wrapper Import

Cause:

The compiled static library and generated python/cwlcovpy.pxd were built with different structure declarations or addon settings.

Fix:

Rebuild from a clean tree:

make clean
make PYTHON=python3 all

Parameter File Tags Not Recognized

Cause:

Parameter files must use full parameter names. Aliases such as root or in are command-line conveniences only.

Fix:

Use names such as rootDir and clsfile in parameter files.

integral Is Zero or NaN

Possible causes:

• ellmin and ellmax fall outside the tabulated clsfile range;

• C_ell contains non-positive values and the log interpolation becomes invalid;

• the input table is not sorted by increasing ell;

• the integration grid is too coarse for the angular scales.

Fix:

Validate the input table and rerun a convergence check over ppp and ellmax.

Build Warnings

The current C build can emit warnings related to unchecked system calls, sprintf format safety, and long logfile paths. They do not block the validated examples, but they should be addressed before hardening the package for automated production pipelines.