smile.math.blas.Diag Maven / Gradle / Ivy

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 * Copyright (c) 2010-2020 Haifeng Li. All rights reserved.
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package smile.math.blas;

/**
 * The flag if a triangular matrix has unit diagonal elements.
 * Some LAPACK routines have an option to handle unit triangular
 * matrices (that is, triangular matrices with diagonal elements = 1).
 * If the matrix is unit triangular, the diagonal elements of
 * the matrix need not be stored, and the corresponding array
 * elements are not referenced by the LAPACK routines.
 * The storage scheme for the rest of the matrix (whether
 * conventional, packed or band) remains unchanged.
 */
public enum Diag {
    /** Non-unit triangular. */
    NON_UNIT(131, (byte) 'N'),
    /** Unit triangular. */
    UNIT(132, (byte) 'U');

    /** Byte value passed to BLAS. */
    private final int blas;
    /** Byte value passed to LAPACK. */
    private final byte lapack;

    /** Constructor. */
    Diag(int blas, byte lapack) {
        this.blas = blas;
        this.lapack = lapack;
    }

    /** Returns the byte value for BLAS. */
    public int blas() { return blas; }

    /** Returns the byte value for LAPACK. */
    public byte lapack() { return lapack; }
}