Hi Luis and Hernán, thank you both for commenting, I'll give it a try! -- Eric Wheeler
On Wed, 5 Oct 2022, Luis Mochan wrote: > Maybe rle can gelp get all sign changes, as in your second example: > > pdl> $a=pdl[ 5.3332316, 4.3332316, 3.3332316, 2.3332316, 1.3332316, > 0.33323163, -0.66676837, -1.6667684, -2.6667684, -3.6667684] > pdl> p $a > [ 5.3332316 4.3332316 3.3332316 2.3332316 1.3332316 0.33323163 > -0.66676837 -1.6667684 -2.6667684 -3.6667684] > pdl> p $a<=>0 > [1 1 1 1 1 1 -1 -1 -1 -1] > > $a<=>0 is just the sign of the elements of $a > > pdl> p +($a<=>0)->rle > [6 4] [1 -1] > > which means there are 6 1's followed by 4 -1's > > pdl> ($rle)=($a<=>0)->rle; > > $rle has [6 4] > > pdl> p $rle((0))-1 > 5 > > I choose the first sign change with ((0)) and subtract 1 to get the > index from the number of elements. > > You can put everything together as in > > pdl> p +[($a<=>0)->rle]->[0]->((0))-1 > 5 > > You could generalize this to get further resonances in more > complicated circuits. > > Regards, > Luis > > > On Wed, Oct 05, 2022 at 06:50:32PM -0700, Eric Wheeler wrote: > > Hello all, > > > > I'm trying to find the series resonant frequency of an RF component, which > > is where the component reactance switches from positive to negtive or > > vice-versa. > > > > Given an N-vector PDL of sorted elements, I need to know at what index it > > switches from positive to negative. > > > > Here are some examples; in real life these are real values from physical > > measurements, so they are never going to be nice round integers---but you > > can assume they will be sorted in ascending or descending order. > > > > Example 1: > > > > pdl> p sequence(10)-5 > > [-5 -4 -3 -2 -1 0 1 2 3 4] > > ^^ > > I need to know "index 4" is the place at which it switches. > > > > > > Example 2: > > > > pdl> p ((-sequence(10))+5+rand()) > > [ 5.3332316 4.3332316 3.3332316 2.3332316 1.3332316 0.33323163 > > -0.66676837 -1.6667684 -2.6667684 -3.6667684] > > ^^^^^^^^^^ > > In this floating-point example it would be "index 5" > > > > > > Is there already a "PDL-broadcast-way" of doing this? > > > > How would you do it? > > > > -- > > Eric Wheeler > > > > > > _______________________________________________ > > pdl-general mailing list > > pdl-general@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/pdl-general > > > > -- > > o > W. Luis Mochán, | tel:(52)(777)329-1734 /<(*) > Instituto de Ciencias Físicas, UNAM | fax:(52)(777)317-5388 `>/ /\ > Av. Universidad s/n CP 62210 | (*)/\/ \ > Cuernavaca, Morelos, México | moc...@fis.unam.mx /\_/\__/ > GPG: 791EB9EB, C949 3F81 6D9B 1191 9A16 C2DF 5F0A C52B 791E B9EB > > > _______________________________________________ > pdl-general mailing list > pdl-general@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/pdl-general >
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