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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: RE: sqrt of all elements of a matrix |

Date |
Thu, 17 Nov 2005 11:45:31 -0000 |

Mata Answers This Admirably! . mata : ------------------------------------------------- mata (type end to exit) ------------------ : m = (1,2,3\4,5,6\7,8,9) : sqrt(m) 1 2 3 +-------------------------------------------+ 1 | 1 1.414213562 1.732050808 | 2 | 2 2.236067977 2.449489743 | 3 | 2.645751311 2.828427125 3 | +-------------------------------------------+ Otherwise, in Stata <9, this is essentially the same question as one asked a few days ago. An ancient program to do this, and other _e_lement_w_ise _m_onadic _f_unction problems, is -matewmf-: STB-56 dm79 . . . . . . . . . . . . . . . . . . Yet more new matrix commands (help matcorr, matewmf, matvsort, svmat2 if installed) . . N. J. Cox 7/00 pp.4--8; STB Reprints Vol 10, pp.17--23 commands to produce a correlation matrix, elementwise monadic function of another matrix, selected subsets of matrix rows and columns, vec or vech of a matrix, elements sorted within a vector, matrix from a vector, and commands to save matrices That name is so unlikely that you would never guess it, but . search matrix would have pointed to it. . matrix A = (1,2,3\4,5,6\7,8,9) . matewmf A B , function(sqrt) . mat li B B[3,3] c1 c2 c3 r1 1 1.4142136 1.7320508 r2 2 2.236068 2.4494897 r3 2.6457513 2.8284271 3 -matewmf- as published in STB-56 is about 30 lines long, but can now be written much more concisely: *! 1.1.0 NJC 17 November 2005 *! 1.0.0 NJC 25 January 2000 program matewmf version 8.0 gettoken A 0 : 0 gettoken B 0 : 0, parse(" ,") syntax , Function(str) tempname C mat `C' = `A' forval i = 1/`=rowsof(matrix(`A'))' { forval j = 1/`=colsof(matrix(`A'))' { mat `C'[`i',`j'] = `function'(`A'[`i',`j']) } } mat `B' = `C' /* allows overwriting of either `A' or `B' */ end from which you can see, as would be expected, that the problem boils down to a double loop. Nick n.j.cox@durham.ac.uk I.A.C. van de Snepscheut > Is there a simple way to take the sqrt of all the elements in > a matrix? * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

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