Package com.itextpdf.barcodes.qrcode
Class GF256Poly
java.lang.Object
com.itextpdf.barcodes.qrcode.GF256Poly
Represents a polynomial whose coefficients are elements of GF(256).
Instances of this class are immutable.
Much credit is due to William Rucklidge since portions of this code are an indirect port of his C++ Reed-Solomon implementation.
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Field Summary
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescription(package private) GF256Poly
addOrSubtract
(GF256Poly other) GF addition or subtraction (they are identical for a GF(2^n)(package private) GF256Poly[]
(package private) int
evaluateAt
(int a) (package private) int
getCoefficient
(int degree) (package private) int[]
(package private) int
(package private) boolean
isZero()
(package private) GF256Poly
multiply
(int scalar) GF scalar multiplication(package private) GF256Poly
GF multiplication(package private) GF256Poly
multiplyByMonomial
(int degree, int coefficient) toString()
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Field Details
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field
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coefficients
private final int[] coefficients
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Constructor Details
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GF256Poly
GF256Poly(GF256 field, int[] coefficients) - Parameters:
field
- theGF256
instance representing the field to use to perform computationscoefficients
- coefficients as ints representing elements of GF(256), arranged from most significant (highest-power term) coefficient to least significant- Throws:
IllegalArgumentException
- if argument is null or empty, or if leading coefficient is 0 and this is not a constant polynomial (that is, it is not the monomial "0")
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Method Details
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getCoefficients
int[] getCoefficients() -
getDegree
int getDegree()- Returns:
- degree of this polynomial
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isZero
boolean isZero()- Returns:
- true iff this polynomial is the monomial "0"
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getCoefficient
int getCoefficient(int degree) - Returns:
- coefficient of x^degree term in this polynomial
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evaluateAt
int evaluateAt(int a) - Returns:
- evaluation of this polynomial at a given point
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addOrSubtract
GF addition or subtraction (they are identical for a GF(2^n)- Parameters:
other
- the other GF-poly- Returns:
- new GF256Poly obtained by summing this GF and other
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multiply
GF multiplication- Parameters:
other
- the other GF-poly- Returns:
- new GF-poly obtained by multiplying this with other
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multiply
GF scalar multiplication- Parameters:
scalar
- scalar- Returns:
- new GF-poly obtained by multiplying every element of this with the scalar.
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multiplyByMonomial
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divide
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toString
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