github.com/consensys/gnark-crypto@v0.14.0/ecc/bw6-761/fp/bw6_utils.go (about)

     1  // Copyright 2020 ConsenSys AG
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package fp
    16  
    17  // MulByNonResidue multiplies a fp.Element by -4
    18  func (z *Element) MulByNonResidue(x *Element) *Element {
    19  	z.Double(x).Double(z).Neg(z)
    20  	return z
    21  }
    22  
    23  // MulByNonResidueInv multiplies a fp.Element by (-4)**-1
    24  func (z *Element) MulByNonResidueInv(x *Element) *Element {
    25  
    26  	nrInv := Element{
    27  		8571757465769615091,
    28  		6221412002326125864,
    29  		16781361031322833010,
    30  		18148962537424854844,
    31  		6497335359600054623,
    32  		17630955688667215145,
    33  		15638647242705587201,
    34  		830917065158682257,
    35  		6848922060227959954,
    36  		4142027113657578586,
    37  		12050453106507568375,
    38  		55644342162350184,
    39  	}
    40  
    41  	z.Mul(x, &nrInv)
    42  
    43  	return z
    44  }