## Operator symbols

Surely I am not the first comic geek to study linear algebra who looked at the symbol for direct sums [see here] and thought, “That’s just the symbol for the X-Men rotated 45 degrees.”

This, of course, makes me wonder what superpowers the mutant known as Direct Sum would have.

There are, in fact, Unicode symbols for “circled plus” (used for the Direct Sum operator) and also “circled times” (though I’m not clear on what operator the latter is used for):

⊕ ⊗ vs. + ×

On the X-Men, see this 10/27/17 posting (which is mostly about the names of bulbs). Their symbol of course incorporates an X:

An assortment of X-Men logos in different colors

Operator symbols. + × – ÷ are standard symbols for arithmetic operators (and are often extended to other mathematical operators); + (plus) and – (minus) are firmly fixed in arithmetic, but × (times) and ÷ (divided-by) have alternative forms: × and ∙ (dot) ∘ (ring) ∗ (asterisk) for multiplication, ÷ and / (slash) for division.

Unicode (and my Apple computer) make more circled operator symbols, beyond the two above, available:

circled dot ⊙ circled ring ⊚ – circled asterisk ⊛ – circled equals ⊜ – circled division slash ⊘ – circled minus ⊖

and some squared operator symbols:

squared plus ⊞ – squared times ⊠ – squared asterisk ⧆ – squared circle ⧇ – squared minus ⊟ – squared dot ⊡ – squared slash ⧄ – squared backslash ⧅

and some operator symbols in triangles:

plus in triangle ⨹ – minus in triangle ⨺ – times in triangle ⨻

and at least one operator symbol in a diamond:

dot in diamond ⟐

I have no idea if these already have conventional uses, but they’re available if you want them.

### One Response to “Operator symbols”

1. arnold zwicky Says:

Jeff Cours on Facebook, responding to Kim’s original question:

What? Two days and no responses to your question? Clearly we need to step it up!
The brilliant Kat Johnson’s ability to integrate abstract mathematics with concrete reality gave her surprising and often unorthodox powers, such as performing arbitrary linear coordinate tranformations of physical objects, effectively teleporting them. Frustrated that few would listen to her and even fewer could understand her, she initially allied herself with Magneto under the nom-de-guerre “Tensor”. However, in later issues she increasingly worked with the X-Men, becoming particularly close to Charles Xavier and Jean Grey, and eventually joined them as “Direct Sum”.