These commands produce roman function names in math mode with proper spacing.

`\arccos`

¶Inverse cosine

`\arcsin`

¶Inverse sine

`\arctan`

¶Inverse tangent

`\arg`

¶Angle between the real axis and a point in the complex plane

`\bmod`

¶Binary modulo operator, used as in

`\( 5\bmod 3=2 \)`

`\cos`

¶Cosine

`\cosh`

¶Hyperbolic cosine

`\cot`

¶Cotangent

`\coth`

¶Hyperbolic cotangent

`\csc`

¶Cosecant

`\deg`

¶Degrees

`\det`

¶Determinant

`\dim`

¶Dimension

`\exp`

¶Exponential

`\gcd`

¶Greatest common divisor

`\hom`

¶Homomorphism

`\inf`

¶Infimum

`\ker`

¶Kernel

`\lg`

¶Base 2 logarithm

`\lim`

¶Limit

`\liminf`

¶Limit inferior

`\limsup`

¶Limit superior

`\ln`

¶Natural logarithm

`\log`

¶Logarithm

`\max`

¶Maximum

`\min`

¶Minimum

`\pmod`

¶Parenthesized modulus, as used in

`\( 5\equiv 2\pmod 3 \)`

`\Pr`

¶Probability

`\sec`

¶Secant

`\sin`

¶Sine

`\sinh`

¶Hyperbolic sine

`\sup`

¶Supremum sup

`\tan`

¶Tangent

`\tanh`

¶Hyperbolic tangent

The `amsmath`

package adds improvements on some of these, and
also allows you to define your own. The full documentation is on CTAN,
but briefly, you can define an identity operator with
`\DeclareMathOperator{\identity}{id}`

that is like the ones
above but prints as ‘`id`’. The starred form
`\DeclareMathOperator*{\op}{op}`

sets any superscript or
subscript to be above and below, as is traditional with `\lim`

,
`\sup`

, or `\max`

.