From maechler at stat.math.ethz.ch  Fri Aug 29 13:56:02 2008
From: maechler at stat.math.ethz.ch (Martin Maechler)
Date: Fri, 29 Aug 2008 13:56:02 +0200
Subject: [Rd] non user-friendly error for chol2inv functions
In-Reply-To: <c8e8cd3d0808290344p305ff0f0q8bb6aa328ece82ad@mail.gmail.com>
References: <c8e8cd3d0808290344p305ff0f0q8bb6aa328ece82ad@mail.gmail.com>
Message-ID: <18615.58322.197666.775061@stat.math.ethz.ch>

>>>>> "cd" == christophe dutang <dutangc at gmail.com>
>>>>>     on Fri, 29 Aug 2008 12:44:18 +0200 writes:

    cd> Hi,
    cd> In function chol2inv with the option LINPACK set to false (default), it
    cd> raises an error when the matrix is 1x1 matrix (i.e. just a real) saying

    cd> 'a' must be a numeric matrix

It is very helpful, but you have to read and understand it.
I'm pretty sure you did not provide a  1 x 1 matrix.

Here's an example showing how things works :

> m <- matrix(4,1,1)
> cm <- chol(m)
> cm
     [,1]
[1,]    2
> chol2inv(cm)
     [,1]
[1,] 0.25
> 

Martin Maechler, ETH Zurich


    cd> This error is raised by the underlying C function (modLa_chol2inv in
    cd> function Lapack.c). Everything is normal, but I wonder if we could have
    cd> another behavior when we pass a 1x1 matrix. I spent time this morning
    cd> finding where was the error, and it was this "problem".

    cd> Thanks in advance

    cd> Christophe

    cd> [[alternative HTML version deleted]]

    cd> ______________________________________________
    cd> R-devel at r-project.org mailing list
    cd> https://stat.ethz.ch/mailman/listinfo/r-devel



[Rd] non user-friendly error for chol2inv functions
Martin Maechler