# [R] Having problems with the ifelse and negative numbers

Richard M. Heiberger rmh @end|ng |rom temp|e@edu
Mon Dec 9 19:25:54 CET 2019

or even simpler
sqrt(abs(A))

On Mon, Dec 9, 2019 at 8:45 AM Eric Berger <ericjberger using gmail.com> wrote:
>
> Hi Bob,
> You wrote "the following error message" -
> when in fact it is a Warning and not an error message. I think your
> code does what you hoped it would do, in the sense it successfully
> calculates the sqrt(abs(negativeNumber)), where appropriate.
>
> If you want to run the code without seeing this warning message you can run
>
> ifelse( A < 0, suppressWarnings(sqrt(-A)), A )
>
> and you should be fine.
>
> HTH,
> Eric
>
> On Mon, Dec 9, 2019 at 3:18 PM Kevin Thorpe <kevin.thorpe using utoronto.ca> wrote:
> >
> > The sqrt(-A) is evaluated for all A. The result returned is conditional on the first argument but the other two arguments are evaluated on the entire vector.
> >
> > Kevin
> >
> > --
> > Kevin E. Thorpe
> > Head of Biostatistics,  Applied Health Research Centre (AHRC)
> > Li Ka Shing Knowledge Institute of St. Michael's
> > Assistant Professor, Dalla Lana School of Public Health
> > University of Toronto
> > email: kevin.thorpe using utoronto.ca  Tel: 416.864.5776  Fax: 416.864.3016
> >
> >
> > ﻿On 2019-12-09, 7:58 AM, "R-help on behalf of rsherry8" <r-help-bounces using r-project.org on behalf of rsherry8 using comcast.net> wrote:
> >
> >     Please consider the following two R statements:
> >          A =  runif(20, min=-1,max=1)
> >          ifelse( A < 0, sqrt(-A), A )
> >
> >     The second statement produces the following error message:
> >          rt(-A) : NaNs produced
> >
> >     I understand that you cannot take the square root of a negative number
> >     but I thought the condition A < 0
> >     would take care of that issue. It appears not to be.
> >
> >     What am I missing?
> >
> >     Thanks,
> >     Bob
> >
> >     ______________________________________________
> >     R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
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> >     and provide commented, minimal, self-contained, reproducible code.
> >
> >
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