In #544, minimum and maximum functions have been accepted for CSS Values Level 4.
Both functions select a single computed value from a set of 1 to N values (which may be results of nested calc() expressions). This cannot be achieved with Level 3 calc() syntax.

• min (minimum/minimal) chooses the smallest computed value.
• max (maximum/maximal) chooses the largest computed value.

min(100px 10em 1vw)
max(100px 10em 1vw)
    
min(100px 10px 1px) /* = 1px */
max(100px 10px 1px) /* = 100px */

There are at least two other useful statistic measures that work the same:

• mode chooses the most frequently occuring computed value.
• median chooses the computed value with the same number of smaller and larger sibling values.

mod(100px 10em 1vw)
med(100px 10em 1vw)

mod(100px 10px 10px) /* = 10px */
med(100px 10px 1px) /* = 10px */

Mode

The mode function may benefit from an optional value to specify the precision, i.e. tolerance limits, when comparing (and returning) computed values.

mod(100px 10em 1vw, 1pt)

This could effectively be reused as a ‘round to nearest multiple’ function. Such a static factor is called a module or modulus, e. g. in architecture and design.

mod(101px, 1pt) /* = 76pt ≈ 101.33px */
mod(100px, 1pt) /* = 75pt = 100px */
mod(99px, 1pt) /* = 74pt ≈ 98.67px */
mod(10px, 1pt) /* = 8pt ≈ 10.67px */
mod(1px, 1pt) /* = 1pt ≈ 1.33px */

The specification must also say what to do if no computed value occurs more often than another. It may fall back to the arithmetic mean of all equally frequent values.

mod(100px 10px) /* = 55px? */

Median

The median function needs to be specified for an even number of values as well, i.e. when there is one above and one below but none at the center of the set. It may fall back to the arithmetic mean of the two values closest to the true median.

med(100px 10px) /* = 55px? */

The median could also be specified for a reduced set where redundant entries were collapsed into a unique one beforehand:

med(1000px 100px 10px 5px 1px)   /* = 10px */
med(1000px 100px 10px 10px 1px)  /* = 10px or: */  med(1000px 100px 10px 1px) /* = 55px */
med(1000px 100px 100px 10px 1px) /* = 100px or: */ med(1000px 100px 10px 1px) /* = 55px */
med(1000px 500px 100px 10px 1px) /* = 100px */

If the values closest to the center do not occur equally often, the median could be weighted instead.

med(1000px 100px 10px 1px)   /* = 110px/2 = 55px */
med(1000px 100px 10px 10px)  /* = 120px/3 = 40px? */
med(100px 100px 10px 1px)    /* = 210px/3 = 70px? */