From mathematics:

"Tensors eat vectors and spit out numbers."

Is this an analogy, metaphor or other named figure of speech?

  • 7
    It is a metaphor. I am not the mathematician to explain. But, as I understand it tensors are operators which operate on (’eat’) vectors and yield (‘spit out’) a number.
    – Tuffy
    Jun 12, 2019 at 20:43
  • I'm not looking for an explanation of the mathematics, just what sort of literary device this is, and why. Thanks.
    – Peter4075
    Jun 13, 2019 at 13:42
  • 1
    I'd agree with Tuffy. A tensor is a creature that eats... would undoubtedly be a metaphor. I don't see any real difference between that and your sentence, although if you went by definitions that require the substituted phenomenon to be mentioned explicitly, you'd have to say it doesn't qualify and belongs to the wider category of 'analogy'.
    – user339660
    Jun 15, 2019 at 9:16
  • It's a metaphor. Eat is restricted to animate subjects. You can't even use it literally with subjects that are alive but don't belong to the animal kingdom. Any non-literal use is a metaphor. Jun 17, 2019 at 14:54
  • It's algebraic -- it's a meta-N, not a metafour.
    – Hot Licks
    Jun 22, 2019 at 0:31

2 Answers 2


The literary device used is called: 1) zoomorphism, giving animal characteristics to something that is not an animal.

Alternatively, it could be called 2) personification as well, if you consider eating and spitting out as applying to humans. Somehow the verbs eat and spit out made me think of animals first. But I guess humans are animals, too.

"Tensors eat vectors and spit out numbers."

Is like a transformation of: "Lions eat gazelles and spit out their bones."

I am sure one can come up with many other images. Here's another:

1) Cats eat mice and spit out the bones. [animal]

2) Men eat fish and spit out the bones. [human]

Both are explained in the link below and I liked the cat picture (though nothing beats the disappearing Cheshire cat in Alice in Wonderland, whose smile is left behind).


But the real delight there is: chremamorphism:

"Can the qualities of inanimate objects be attributed to humans, and animals? Yes, they can, and this technique is called chremamorphism."

Mine: He started rattling, let out a prolonged cranking noise and fell silent.

Yes, these are all metaphors in that they create an image of an animal or human or thing but they are also specific literary devices. Metaphors can be created in any number of ways, all of which I am not going to go into here. Literary devices can get very complicated. A good reference handbook for everyone to have in their personal library is "The Oxford Book of Literary Terms", which is now in its fourth edition.

Analogies are comparisons. There is no comparison here. There's substitution of technical verbs for verbs associated with eating and animals. That's metaphor as the image is created of an animal through the use of the verbs.

[Editing Note: I just realized I had made a mistake in my example above so I corrected it. See chremamorphism.]

  • 2
    Zoomorphism is not commonly recognized in this context and is just a specific kind of metaphor. It's better to call it a metaphor.
    – R Mac
    Jun 19, 2019 at 2:48
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    @RMac Oh for pete's sake. The poetic device here is personification or zoomorphism: tensors are being said to eat something and spit it out. "tensor" has been personified or zoomorphized. Who exactly eats and spits out stuff? People, animals, maybe even certain bacteria. For the latter, I'd have to ask a biologist.
    – Lambie
    Jun 21, 2019 at 15:20
  • Lambie, I think there's room for you to strengthen this answer. Please don't get defensive -- this is intended as a constructive suggestion. First suggestion: maybe think about the sentence as a mixed metaphor. The spitting out is kind of separate from the eating. "Eating" is the explainer's way of talking about input, and "spitting out" is the explainer's way of talking about output. Second suggestion: How about you start with a succinct intro to your answer, talking about metaphors in general, with maybe an example? Then, you could certainly get into specifics about exactly... Jun 23, 2019 at 14:40
  • ... what type of metaphor(s) is/are involved. Jun 23, 2019 at 14:40
  • @aparente001 I am not defensive but I really find it a bit odd that you are trying to get me to "improve my answer" by suggesting something that is a mistaken reading of the sentence. There is no mixed metaphor here at all: eat and spit out collocate to a single activity: carnivores eating. As for talking about metaphors in general, I already discussed that. It would take a book and here the poetic device is personification, one of the ways to create metaphor. Two verbs relating to the same activity do not a mixed metaphor make.
    – Lambie
    Jun 23, 2019 at 15:01

Answer: It's a metaphor.

Disclaimer: I am not a mathematician.

Explanation: Keep reading.

From what I understand of tensors, they are geometric objects that are made up of vector and numerical (coordinate) components. (Source: https://www.youtube.com/watch?v=TvxmkZmBa-k) Knowing this helps us establish that the subject (tensors) and objects (vectors, numbers) in this fascinating sentence are indeed 'real'. They do actually mean tensors, vectors and numbers.

Now let's look at the verbs, 'eat' and 'spit out'. These are typically actions that animals, humans included, perform. This is not 'real'; tensors cannot eat or spit, but these actions have been assigned to tensors. We call this zoomorphism or personification.

The purpose of this sentence is to establish the relationship between three things: one where there is a certain input and a different, processed output. This is similar to the process of eating and spitting out. Rather than just say that tensors are like humans, vectors are like chicken wings, and numbers are like bones, this sentence uses zoomorphism/personification to liken the relationship between the three things to a person eating chicken wings without an explicit statement of said similarity.

This is very the definition of a metaphor - it is an implicit comparison made by applying an action/quality to an object to which said action/quality is literally inapplicable. Typically, with any metaphor, you can deconstruct it to reveal clear parallels, which will invariably use the words "like", "as", "similar" etc. (which I've just done with the humans, chicken wings, and bones example).

UPDATE: On further reading, I've found that while the above definition of a metaphor is its most common, the word actually encapsulates "all figures of speech that achieve their effect through association, comparison, and resemblance" according to The Oxford Companion to the English Language (1992) pp.653–55. (Source: https://english.stackexchange.com/a/3871/155273)
Meanwhile, an analogy is more of a logical argument that focuses on shared characteristics of two (or more) things, to establish that they are alike. It isn't a figure of speech. That's further evidence that this sentence is in fact a metaphor, and not an analogy.

Forget the mathematics. Just think in terms of something eating something else and spitting out numbers. If this is a metaphor, why is it a metaphor? If it isn't a metaphor, what is it?

I understand this as a note to focus on the language and imagery, rather than on the maths, which I agree with fully. However, you can't ignore the context and expect to find the right answer. It's not the act of eating one thing and spitting out another that makes this sentence a metaphor; it's the fact that the 'eating' and 'spitting' are being done by a thing that, in reality, cannot eat or spit.

If your real question is, 'What is the figure of speech that describes this act of eating one thing and spitting out another?' I think the closest answer would be digestion, or a lack thereof.

UPDATE 2: I'm joking about the digestion bit. Of course it isn't a figure of speech!

  • Of course, it is a metaphor. But metaphors come in many shapes and sizes. digesting cannot be a figure of speech here. digesting as a figure of speech would be: He had to digest what his boss said before beginning the task. The image here is of an animal or human who doesn't consume the bones of the meat they are eating. In short: carnivores.
    – Lambie
    Jun 22, 2019 at 14:21
  • @Lambie I was joking when I said digestion.
    – karish10
    Jun 23, 2019 at 7:55
  • You have misunderstood me completely. The metaphor here is carnivores. Not digestion per se.
    – Lambie
    Jun 23, 2019 at 14:19
  • Carnivores don’t necessarily spit their food out. And herbivores could spit things out too, if they so wished. What they’re all doing is eating, or processing, or rather semi-processing since they’re still spitting something out. Hence, I said digestion (or not). Ultimately though, digestion could be the metaphor, but not the type of figure of speech (which is ostensibly what the OP is asking about).
    – karish10
    Jun 23, 2019 at 22:11

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