Definitions
from The American Heritage® Dictionary of the English Language, 4th Edition
 n. A plural of matrix.
from Wiktionary, Creative Commons Attribution/ShareAlike License
 n. Plural form of matrix.
from The Century Dictionary and Cyclopedia
 n. Plural of matrix.
Etymologies
Sorry, no etymologies found.
Examples

This is the crucial point: the MBH98 reconstruction has to use the S1 and V1 matrices from the short observed period SVD not the S_full and V_full of the full period SVD.

Mtheory appears to have the property that what we perceive as position and time, that is, the coordinates of a string or a brane, are really mathematical arrays known as matrices.

Included in the exhibition are three monumental woodblocks (called matrices), measuring

Mechanical quantities, such as position, velocity, etc. should be represented, not by ordinary numbers, but by abstract mathematical structures called "matrices" and he formulated his new theory in terms of matrix equations.

The Tariff Commission Report and minutes of evidence (AJHR H. 2, 1895) includes some very useful detail on what was imported (such as matrices of advertising matter, printing blocks and printed sheets of letterheads and invoices) and its relationship with the manufacturing capabilities of the New Zealand industry.
Book & Print in New Zealand: A Guide to Print Culture in New Zealand

A '' 'matrix' '' (pl.: "matrices," [[Latin]] origin) is a complex ordering, in deliberate fashion, of [[numeral  numerals]]

Given the good condition of the lead 'matrices', one must conclude that an attempt to cast type in them has never been made.

Enschedé en Zonen in Haarlem of which the height of the face measures 16 mm and for which there are 'matrices' in brass and lead, and relief 'punches', also of brass.

You can plot 2D graphs and you can work with matrices, do complex integrals, calculate very large factorials, and that's the most simple stuff. try matrices: or differential equations:
First Look At Wolfram Alpha’s Impressive Knowledge Computation  Lifehacker Australia

Law schools publish matrices of admissions percentages at various GPA/LSAT levels, and most of them have fairly hard cutoffs in which minor differentials matter quite a bit.
The Volokh Conspiracy » Do Law Schools Seek “Exciting” and “Diverse” Students?
bilby commented on the word matrices
... is an abomination, until somebody forks over the dagnabbit plural.
June 16, 2009
plethora commented on the word matrices
WeetBix are an abomination.
June 16, 2009
fbharjo commented on the word matrices
what a fine web of webs this is. or should it be webx of webces
June 16, 2009
bilby commented on the word matrices
I'll need to know the plural of WeetBix before breakfast time. Thank you.
June 16, 2009
qroqqa commented on the word matrices
Asteriges (based on the actual genitive of Vercingetorix): the stem ends in the Gaulish element rig "ruler".
June 16, 2009
Prolagus commented on the word matrices
Ha ha!
June 16, 2009
rolig commented on the word matrices
So what would be the plural of asterix?
June 16, 2009
qroqqa commented on the word matrices
That's right: the trix in all these is the female agent ending (feminine of tor), so they all go the same.
I should add that the traditional English pronunciation would be /'traɪsiːz/ with shift of stress to the long vowel, but the most common one, matrices, is now firmly established with stress the same as the singular, so that might be preferable for all the others too.
June 15, 2009
pterodactyl commented on the word matrices
What's the correct way to pluralize "dominatrix"? My college friends and I used "dominatrices", but that may have just been wishful thinking.
And what about "aviatrix"?
June 15, 2009
madmouth commented on the word matrices
Not as Slavishly Pluralized as They Look
June 15, 2009
charlesferdinand commented on the word matrices
Forming Hendrices from Hendrix, now that would be a slavish pluralisation.
June 15, 2009
qroqqa commented on the word matrices
Latin matrix has a stem ending in /i:k/ and regularly forms its nominative by adding /s/. So also the mathematical term 'directrix' ~ 'directrices', as well as rare female agent nouns such as 'executrix'.
Vertex (doublet of vortex in Latin) owes its stem vowel to the fact that in Old Latin unstressed short vowels before a single consonant became /i/, thus plural /wertike:s/; but before two consonants, /e/, thus /werteks/. So also 'apex' ~ 'apices'. This alternation didn't apply to the long /i:/ of /ma:tri:ks/ ~ /ma:tri:ke:s/.
June 15, 2009
sionnach commented on the word matrices
I'm not sure why you consider this an example of slavish pluralization.
'matrix' is a third declension Latin noun, with the following case forms:
*** Singular Plural
nom. m�?trix m�?trīcēs
gen. m�?trīcis m�?trīcum
dat. m�?trīcī m�?trīcibus
acc. m�?trīcem m�?trīcēs
abl. m�?trīce m�?trīcibus
voc. m�?trix m�?trīcēs
Thus, 'matrices' is the correct plural form.
Similarly, 'vertices' is the correct plural form of 'vertex', because vertex is also a third declension noun. The difference in vowels in the singular ending is immaterial, and not  as you suggest  'crucial'.
June 15, 2009
madmouth commented on the word matrices
part of the slavish pluralization phenomenon. I presume the math world got 'matrices' from 'vertices', though the two have crucially different singular endings.
June 15, 2009