Struct PermutFn 

pub struct PermutFn;

Trait Implementations

impl Debug for PermutFn

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Function for PermutFn

Returns the number of permutations for selecting and ordering k items from n.

PERMUT computes n!/(n-k)! after truncating both inputs toward zero.

Remarks

• Fractional inputs are truncated to integers.
• If n < 0, k < 0, or k > n, the function returns #NUM!.
• Argument errors propagate directly.

Examples

title: "Basic permutations"
formula: "=PERMUT(5, 2)"
expected: 20

title: "Fractional arguments are truncated"
formula: "=PERMUT(7.9, 3.1)"
expected: 210

title: "Out-of-range k returns numeric error"
formula: "=PERMUT(4, 6)"
expected: "#NUM!"

related:
  - COMBIN
  - FACT
  - MULTINOMIAL
faq:
  - q: "Why does PERMUT fail when k is larger than n?"
    a: "Permutations require choosing at most n items, so k > n returns #NUM!."
  - q: "How are decimal inputs handled?"
    a: "PERMUT truncates n and k toward zero before computing n!/(n-k)!."

[formualizer-docgen:schema:start] Name: PERMUT Type: PermutFn Min args: 2 Max args: 2 Variadic: false Signature: PERMUT(arg1: number@scalar, arg2: number@scalar) Arg schema: arg1{kinds=number,required=true,shape=scalar,by_ref=false,coercion=NumberLenientText,max=None,repeating=None,default=false}; arg2{kinds=number,required=true,shape=scalar,by_ref=false,coercion=NumberLenientText,max=None,repeating=None,default=false} Caps: PURE [formualizer-docgen:schema:end]

fn caps(&self) -> FnCaps

Capability flags for this function

fn name(&self) -> &'static str

fn min_args(&self) -> usize

fn arg_schema(&self) -> &'static [ArgSchema]

fn eval<'a, 'b, 'c>( &self, args: &'c [ArgumentHandle<'a, 'b>], _: &dyn FunctionContext<'b>, ) -> Result<CalcValue<'b>, ExcelError>

The unified evaluation path.

fn namespace(&self) -> &'static str

fn variadic(&self) -> bool

fn volatile(&self) -> bool

fn aliases(&self) -> &'static [&'static str]

Optional list of additional alias names (case-insensitive) that should resolve to this function. Default: empty slice. Implementors can override to expose legacy names. Returned slice must have ’static lifetime (typically a static array reference).

fn function_salt(&self) -> u64

fn eval_reference<'a, 'b, 'c>( &self, _args: &'c [ArgumentHandle<'a, 'b>], _ctx: &dyn FunctionContext<'b>, ) -> Option<Result<ReferenceType, ExcelError>>

Optional reference result path. Only called by the interpreter/engine when the callsite expects a reference (e.g., range combinators, by-ref argument positions, or spill sources).

fn dispatch<'a, 'b, 'c>( &self, args: &'c [ArgumentHandle<'a, 'b>], ctx: &dyn FunctionContext<'b>, ) -> Result<CalcValue<'b>, ExcelError>

Dispatch to the unified evaluation path with automatic argument validation.