Struct GoldschmidtDivision 

pub struct GoldschmidtDivision {
    pub iterations: u64,
    pub denominator_cap_2k: u64,
}

A structure that defines the custom operation GoldSchmidtDivision that computes division of two numbers via the Goldschmidt method.

In particular, this operation computes an approximation of 2^{denominator_cap_2k} divdend / divisor.

Inputs must be of the scalar type UINT64 or INT64 and be in (0, 2^{denominator_cap_2k - 1}) range. The divisor is also assumed to be small enough (less than 2³²), otherwise integer overflows are possible, yielding incorrect results.

Optionally, an initial approximation for the Goldschmidt method can be provided. In this case, the operation might be faster and of lower depth, however, it must be guaranteed that 2^{denominator_cap_2k - 1} <= input * initial_approximation < 2^{denominator_cap_2k + 1}.

Custom operation arguments

• Node containing an unsigned or signed 64-bit array or scalar as the dividend.
• Node containing an unsigned or signed 64-bit array or scalar as the divisor.
• Negative values are currently unsupported as sign extraction is quite expensive
• (optional) Node containing an array or scalar that serves as an initial approximation of the GoldSchmidt method

Custom operation returns

New GoldschmidtDivision node

Example

let c = create_context().unwrap();
let g = c.create_graph().unwrap();
let t = array_type(vec![2, 3], UINT64);
let dividend = g.input(t.clone()).unwrap();
let divisor = g.input(t.clone()).unwrap();
let guess_n = g.input(t.clone()).unwrap();
let n2 = g.custom_op(CustomOperation::new(GoldschmidtDivision {iterations: 10, denominator_cap_2k: 4}), vec![dividend,divisor, guess_n]).unwrap();

Fields

iterations: u64

Number of iterations of the Goldschmidt method; rule of thumb is to set it to 1 + log(denominator_cap_2k)

denominator_cap_2k: u64

Number of output bits that are approximated

Trait Implementations

impl CustomOperationBody for GoldschmidtDivision

fn instantiate( &self, context: Context, arguments_types: Vec<Type>, ) -> Result<Graph>

Defines the logic of a custom operation.

fn get_name(&self) -> String

Specifies and returns the name of this custom operation.

impl Debug for GoldschmidtDivision

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for GoldschmidtDivision

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Hash for GoldschmidtDivision

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for GoldschmidtDivision

fn eq(&self, other: &GoldschmidtDivision) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for GoldschmidtDivision

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Eq for GoldschmidtDivision

impl StructuralPartialEq for GoldschmidtDivision