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//
// GENERATED FILE
//
use super::*;
use crate::SpiceContext;
use f2rust_std::*;
/// Return the 3x3 identity matrix
///
/// Return the 3x3 identity matrix.
///
/// # Brief I/O
///
/// ```text
/// VARIABLE I/O DESCRIPTION
/// -------- --- --------------------------------------------------
/// MATRIX O The 3x3 identity matrix.
/// ```
///
/// # Detailed Output
///
/// ```text
/// MATRIX is the 3x3 Identity matrix. That MATRIX is
/// the following
///
/// .- -.
/// | 1.0D0 0.0D0 0.0D0 |
/// | 0.0D0 1.0D0 0.0D0 |
/// | 0.0D0 0.0D0 1.0D0 |
/// `- -'
/// ```
///
/// # Exceptions
///
/// ```text
/// Error free.
/// ```
///
/// # Particulars
///
/// ```text
/// This is a utility routine for obtaining the 3x3 identity matrix
/// so that you may avoid having to write the loop or assignments
/// needed to get the matrix.
/// ```
///
/// # Examples
///
/// ```text
/// The numerical results shown for this example may differ across
/// platforms. The results depend on the SPICE kernels used as
/// input, the compiler and supporting libraries, and the machine
/// specific arithmetic implementation.
///
/// 1) Define a 3x3 matrix and compute its inverse using the SPICELIB
/// routine INVERT. Verify the accuracy of the computed inverse
/// using the mathematical identity
///
/// -1
/// M x M - I = 0
///
/// where I is the 3x3 identity matrix.
///
///
/// Example code begins here.
///
///
/// PROGRAM IDENT_EX1
/// IMPLICIT NONE
///
/// C
/// C Local variables.
/// C
/// DOUBLE PRECISION IDMAT ( 3, 3 )
/// DOUBLE PRECISION IMAT ( 3, 3 )
/// DOUBLE PRECISION M ( 3, 3 )
/// DOUBLE PRECISION MOUT ( 3, 3 )
/// DOUBLE PRECISION MZERO ( 3, 3 )
///
/// INTEGER I
/// INTEGER J
///
/// C
/// C Define a matrix to invert.
/// C
/// DATA M / 0.D0, 0.5D0, 0.D0,
/// . -1.D0, 0.D0, 0.D0,
/// . 0.D0, 0.D0, 1.D0 /
///
/// WRITE(*,*) 'Original Matrix:'
/// DO I=1, 3
///
/// WRITE(*,'(3F16.7)') ( M(I,J), J=1,3 )
///
/// END DO
/// C
/// C Invert the matrix, then output.
/// C
/// CALL INVERT ( M, MOUT )
///
/// WRITE(*,*) ' '
/// WRITE(*,*) 'Inverse Matrix:'
/// DO I=1, 3
///
/// WRITE(*,'(3F16.7)') ( MOUT(I,J), J=1,3 )
///
/// END DO
///
/// C
/// C Check the M times MOUT produces the identity matrix.
/// C
/// CALL IDENT ( IDMAT )
/// CALL MXM ( M, MOUT, IMAT )
///
/// CALL VSUBG ( IMAT, IDMAT, 9, MZERO )
///
/// WRITE(*,*) ' '
/// WRITE(*,*) 'Original times inverse minus identity:'
/// DO I=1, 3
///
/// WRITE(*,'(3F16.7)') ( MZERO(I,J), J=1,3 )
///
/// END DO
///
/// END
///
///
/// When this program was executed on a Mac/Intel/gfortran/64-bit
/// platform, the output was:
///
///
/// Original Matrix:
/// 0.0000000 -1.0000000 0.0000000
/// 0.5000000 0.0000000 0.0000000
/// 0.0000000 0.0000000 1.0000000
///
/// Inverse Matrix:
/// 0.0000000 2.0000000 -0.0000000
/// -1.0000000 0.0000000 -0.0000000
/// 0.0000000 -0.0000000 1.0000000
///
/// Original times inverse minus identity:
/// 0.0000000 0.0000000 0.0000000
/// 0.0000000 0.0000000 0.0000000
/// 0.0000000 0.0000000 0.0000000
/// ```
///
/// # Author and Institution
///
/// ```text
/// J. Diaz del Rio (ODC Space)
/// W.L. Taber (JPL)
/// ```
///
/// # Version
///
/// ```text
/// - SPICELIB Version 1.0.1, 03-JUN-2021 (JDR)
///
/// Edited the header to comply with NAIF standard. Added complete
/// code example.
///
/// - SPICELIB Version 1.0.0, 05-FEB-1996 (WLT)
/// ```
pub fn ident(matrix: &mut [[f64; 3]; 3]) {
IDENT(matrix.as_flattened_mut());
}
//$Procedure IDENT ( Return the 3x3 identity matrix )
pub fn IDENT(MATRIX: &mut [f64]) {
let mut MATRIX = DummyArrayMut2D::new(MATRIX, 1..=3, 1..=3);
MATRIX[[1, 1]] = 1.0;
MATRIX[[2, 1]] = 0.0;
MATRIX[[3, 1]] = 0.0;
MATRIX[[1, 2]] = 0.0;
MATRIX[[2, 2]] = 1.0;
MATRIX[[3, 2]] = 0.0;
MATRIX[[1, 3]] = 0.0;
MATRIX[[2, 3]] = 0.0;
MATRIX[[3, 3]] = 1.0;
}