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dev:codingconventions [2018/12/19 12:01]
tmueller reformat
dev:codingconventions [2018/12/21 08:41] (current)
tmueller [Use existing infrastructure]
Line 39: Line 39:
  
 ===== Use existing infrastructure ===== ===== Use existing infrastructure =====
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 +Always prefer [[https://​gcc.gnu.org/​onlinedocs/​gcc-8.2.0/​gfortran/​Intrinsic-Procedures.html|built-in (intrinsic) functions]] instead of hand-coded routines since they usually include extra numerical checks to avoid intermediate under- or overflow while still performing optimally. Examples:
 +
 +  * ''​NORM2(x)''​ instead of ''​%%SQRT(x(1)**2 + x(2)**2 + x(3)**2)%%''​
 +  * ''​DOT_PRODUCT(x,​ x)''​ instead of ''​%%x(1)**2 + x(2)**2 + x(3)**2%%''​
 +  * ''​DOT_PRODUCT(x,​ y)''​ instead of ''​%%x(1)*y(1) + x(2)*y(2) + x(3)*y(3)%%''​
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 +
 For many common operations there exist wrappers in CP2K to prevent usage errors and to allow for central redirections,​ i.e. avoid to use direct calls to external libraries in CP2K For many common operations there exist wrappers in CP2K to prevent usage errors and to allow for central redirections,​ i.e. avoid to use direct calls to external libraries in CP2K
 +
   * Use the routines from ''​cp_files.F''​ instead of calling ''​OPEN''​ and ''​CLOSE''​ directly.   * Use the routines from ''​cp_files.F''​ instead of calling ''​OPEN''​ and ''​CLOSE''​ directly.
   * Use the routines from the full-matrix ''​fm''​-package instead of calling BLAS or Scalapack directly.   * Use the routines from the full-matrix ''​fm''​-package instead of calling BLAS or Scalapack directly.
dev/codingconventions.1545220875.txt.gz ยท Last modified: 2018/12/19 12:01 by tmueller