From octave-sources-request at bevo dot che dot wisc dot edu  Fri Oct 15 07:44:27 1999
Subject: modified kron.m 
From: etienne grossmann <etienne at anonimo dot isr dot ist dot utl dot pt>
To: octave-sources at bevo dot che dot wisc dot edu
CC: etienne at isr dot ist dot utl dot pt
Date: Fri, 15 Oct 1999 13:44:10 +0100 (WEST)

--Multipart_Fri_Oct_15_13:44:09_1999-1
Content-Type: text/plain; charset=US-ASCII



  Hello,

  I have implemented the kronecker product in slightly faster way than
in kron.m : the code is (in fact, there is also an argument check):

  function c = mykron(a,b)
  [ra,ca]=size(a);
  [rb,cb]=size(b);
  
  c = a((ones(rb,1)*[1:ra])(:),(ones(cb,1)*[1:ca])(:)).*...
      b(([1:rb]'*ones(1,ra))(:),([1:cb]'*ones(1,ca))(:));
 

  I a little test seems to show that this is about twice as fast as the
original kron. I attach the files mykron.m, which defines the
function, and test_mykron.m, that checks that the result of kron and
mykron are equal, and times the cpu time.

  Cheers,

  Etienne



--Multipart_Fri_Oct_15_13:44:09_1999-1
Content-Type: application/octet-stream
Content-Disposition: attachment; filename="mykron.m"
Content-Transfer-Encoding: base64
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--Multipart_Fri_Oct_15_13:44:09_1999-1
Content-Type: application/octet-stream
Content-Disposition: attachment; filename="test_mykron.m"
Content-Transfer-Encoding: base64

CjE7CgojIFJldHVybnMgdGhlIGNwdXRpbWUgc2luY2UgbGFzdCAnbXl0aWMnCmZ1bmN0aW9u
IGR0ID0gbXl0aWMoKQkJCiAgc3RhdGljIGxhc3RfbXl0aWMgPSAwIDsKICBbdCx1LHNdID0g
Y3B1dGltZSgpIDsKICBkdCA9IHQgLSBsYXN0X215dGljIDsKICBsYXN0X215dGljID0gdCA7
CmVuZGZ1bmN0aW9uCgp0MSA9IHQyID0gMDsKbnRyaWFscyA9IDEwMDsKcmVzID0gemVyb3Mo
MyxudHJpYWxzKTsKZm9yIGkgPSAxOm50cmlhbHMsCiAgcz1mbG9vcigzMCpyYW5kKDEsNCkp
KzE7CiAgYT1yYW5kbihzKDEpLHMoMikpOwogIGI9cmFuZG4ocygzKSxzKDQpKTsKICByZXMo
MSxpKSA9IHByb2QocykgOwogIG15dGljKCk7CiAgazEgPSBrcm9uKGEsYikgOwogIHJlcygy
LGkpID0gbXl0aWMoKTsKICBrMiA9IG15a3JvbihhLGIpIDsKICByZXMoMyxpKSA9ICBteXRp
YygpOwogIGlmIGFueShtYXgobWF4KGsxLWsyKSkpLAogICAgcHJpbnRmKCJXaG9hISFcbiIp
OwogICAgcHJpbnRmKCJUaGlzIHNob3VsZCBiZSAwIDogJTguM2dcbiIsbWF4KG1heChrMS1r
MikpKTsKICAgIGtleWJvYXJkCiAgZW5kCiAgIyMgcHJpbnRmKCJpPSVkLHNpemVzIDogICVk
IGVsZW1lbnRzXG4iLGkscHJvZChzKSk7CiAgcHJpbnRmKCJ0aW1pbmcgOiBrcm9uOiU4LjNn
ICAgbXlrcm9uOiU4LjNnXG4iLHJlcygyLGkpLHJlcygzLGkpKTsKZW5kCgpiazEgPSByZXMo
Miw6KSA8IHJlcygzLDopIDsJIyBrMSBiZXR0ZXIKZXhlID0gcmVzKDIsOikgPT0gcmVzKDMs
OikgOwkjIGV4LWFlcXVvCnByaW50Zigia3JvbiA6ICVkLCAgZXgtYWVxdW8gJWQsICBteWty
b24gJWRcbiIsLi4uCiAgICAgICBzdW0oYmsxKSxzdW0oZXhlKSxzdW0oMS1iazEpKTsKCnBy
aW50ZigiXG5XaGVuIGtyb24gaXMgYmV0dGVyXG4iKTsKcHJpbnRmKCJNZWFuIHNpemUgOiAl
ZCwgdGltaW5nIDoga3JvbjolOC4zZyAgIG15a3JvbjolOC4zZ1xuIiwuLi4KICAgICAgIG1l
YW4ocmVzKDosZmluZChiazEpKScpKTsKCnByaW50ZigiXG5XaGVuIG15a3JvbiBpcyBiZXR0
ZXJcbiIpOwpwcmludGYoIk1lYW4gc2l6ZSA6ICVkLCB0aW1pbmcgOiBrcm9uOiU4LjNnICAg
bXlrcm9uOiU4LjNnXG4iLC4uLgogICAgICAgbWVhbihyZXMoOixmaW5kKDEtYmsxKSknKSk7
CgpwcmludGYoIlxuQWx0b2dldGhlclxuIik7CnByaW50ZigiTWVhbiBzaXplIDogJWQsIHRp
bWluZyA6IGtyb246JTguM2cgICBteWtyb246JTguM2dcbiIsLi4uCiAgICAgICBtZWFuKHJl
cycpKQoKcGxvdChyZXMoMSw6KSxyZXMoMiw6KSwnb2cnLHJlcygxLDopLHJlcygzLDopLCdv
YicpIDsK

--Multipart_Fri_Oct_15_13:44:09_1999-1--