[R] matrix power

Nordlund, Dan (DSHS/RDA) NordlDJ at dshs.wa.gov
Mon Aug 10 23:52:33 CEST 2009

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
> Behalf Of cindy Guo
> Sent: Monday, August 10, 2009 2:32 PM
> To: r-help at r-project.org
> Subject: [R] matrix power
> Hi, All,
> If I  have a symmetric matrix, how can I get the negative square root of the
> matrx, ie. X^(-1/2) ?
> Thanks,
> Cindy


Just to be sure we are all on the same page.  Are saying you have a matrix X, and you want to find the a matrix A such that

X = A %*% A 

And you want to then find the matrix inverse of A ?


Daniel J. Nordlund
Washington State Department of Social and Health Services
Planning, Performance, and Accountability
Research and Data Analysis Division
Olympia, WA  98504-5204

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