Merge faster Riemann R function #73

Job	Run time
linux_clang (ubuntu-latest, Debug)	3m 27s
linux_gcc_sanitizers	2m 19s
linux_clang (ubuntu-latest, Release)	1m 31s
linux_gcc (ubuntu-latest, Debug)	4m 51s
linux_gcc_valgrind	1m 12s
linux_gcc (ubuntu-latest, Release)	2m 19s
macos_clang (macos-latest, Debug)	5m 55s
windows_mingw64 (windows-latest, Debug)	5m 11s
windows_msvc2022	1m 39s
macos_clang (macos-latest, Release)	58s
windows_mingw64 (windows-latest, Release)	2m 48s
	32m 10s

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