RandVars
RandVars
RandVars[ n ] randomly selects n different variable names.
Usages
RandVars[ n ]
RandVars[ n ] returns a list of n different single-letter variables, chosen from a, m, n, p, s, t and x. Letters that are easily confused with other symbols or in handwriting, such as o, v, q and i, are never chosen. With n = 1, a single variable is returned instead of a list. Each time the exercise is generated, a new choice is made, so the outputs below are only examples.
| Example | in | out |
|---|---|---|
| A single random variable. | RandVars[ 1 ] |
for example m |
3 different variables. |
RandVars[ 3 ] |
for example {p, x, m} |
| Use the variables in an expression. | v := RandVars[2] |
for example e = m+2n |
RandVars[ n, {var1, var2, ...} ]
With a second argument, the variables are chosen from the given list instead.
| Example | in | out |
|---|---|---|
2 variables from p, q and r. |
RandVars[ 2, {p, q, r} ] |
for example {r, p} |
| Longer names are possible. | RandVars[ 2, {alpha, beta, gamma} ] |
for example {gamma, alpha} |
Options
Exclude
A list of letters that must not be chosen. Only used without a second argument.
| Syntax | Example | out |
|---|---|---|
RandVars[ n, Exclude=>{var1, var2, ...} ] |
RandVars[ 3, Exclude=>{x, t} ] |
for example {p, m, a} |
Details
- At most 7 variables can be chosen without a second argument, and fewer when letters are excluded.
- Zero variables:
RandVars[ 0 ]returns{}.
| Invalid input | Result |
|---|---|
RandVars[ 8 ] |
Error: the 1st argument exceeds the number of available variables 7 |
RandVars[ 4, {p, q} ] |
Error: the 1st argument exceeds the number of available variables 2 |
RandVars[ 2, Exclude=>x ] |
Error: The associative argument 'Exclude' should be a list |
RandVars[ x ] |
The script stops with an internal error: n must be an integer. |
See also: RandomSelect, RandomInt