Struct PoissonDistFn 

pub struct PoissonDistFn;

Returns the Poisson probability for event count x at average rate mean.

POISSON.DIST supports exact-count mode (PMF) and cumulative mode (CDF).

Remarks

• x is truncated to an integer and must be at least 0.
• mean must be non-negative.
• Set cumulative to non-zero for CDF mode, or 0 for PMF mode.
• Returns #NUM! for negative counts or negative mean values.

Examples

title: "Poisson PMF for zero events"
formula: "=POISSON.DIST(0,2,FALSE)"
expected: 0.1353352832366127

title: "Poisson CDF up to two events"
formula: "=POISSON.DIST(2,2,TRUE)"
expected: 0.6766764161830634

Trait Implementations

impl Debug for PoissonDistFn

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

Formats the value using the given formatter.

impl Function for PoissonDistFn

[formualizer-docgen:schema:start] Name: POISSON.DIST Type: PoissonDistFn Min args: 3 Max args: 3 Variadic: false Signature: POISSON.DIST(arg1: number@scalar, arg2: number@scalar, arg3: 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}; arg3{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>], _ctx: &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.