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//
// GENERATED FILE
//
use super::*;
use crate::SpiceContext;
use f2rust_std::*;
/// Vector projection, general dimension
///
/// Compute the projection of one vector onto another vector. All
/// vectors are of arbitrary dimension.
///
/// # Brief I/O
///
/// ```text
/// VARIABLE I/O DESCRIPTION
/// -------- --- --------------------------------------------------
/// A I The vector to be projected.
/// B I The vector onto which A is to be projected.
/// NDIM I Dimension of A, B, and P.
/// P O The projection of A onto B.
/// ```
///
/// # Detailed Input
///
/// ```text
/// A is a double precision vector of arbitrary dimension.
/// This vector is to be projected onto the vector B.
///
/// B is a double precision vector of arbitrary dimension.
/// This vector is the vector which receives the
/// projection.
///
/// NDIM is the dimension of A, B and P.
/// ```
///
/// # Detailed Output
///
/// ```text
/// P is a double precision vector of arbitrary dimension
/// containing the projection of A onto B. (P is
/// necessarily parallel to B.)
/// ```
///
/// # Exceptions
///
/// ```text
/// Error free.
/// ```
///
/// # Particulars
///
/// ```text
/// The projection of a vector A onto a vector B is, by definition,
/// that component of A which is parallel to B. To find this
/// component it is enough to find the scalar ratio of the length of
/// B to the projection of A onto B, and then use this number to
/// scale the length of B. This ratio is given by
///
/// RATIO = < A, B > / < B, B >
///
/// where <,> denotes the general vector dot product. This routine
/// does not attempt to divide by zero in the event that B is the
/// zero vector.
/// ```
///
/// # 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 two sets of vectors and compute the projection of
/// each vector of the first set on the corresponding vector of
/// the second set.
///
/// Example code begins here.
///
///
/// PROGRAM VPROJG_EX1
/// IMPLICIT NONE
///
/// C
/// C Local parameters.
/// C
/// INTEGER NDIM
/// PARAMETER ( NDIM = 4 )
///
/// INTEGER SETSIZ
/// PARAMETER ( SETSIZ = 4 )
///
/// C
/// C Local variables.
/// C
/// DOUBLE PRECISION SETA ( NDIM, SETSIZ )
/// DOUBLE PRECISION SETB ( NDIM, SETSIZ )
/// DOUBLE PRECISION PVEC ( NDIM )
///
/// INTEGER I
/// INTEGER M
///
/// C
/// C Define the two vector sets.
/// C
/// DATA SETA / 6.D0, 6.D0, 6.D0, 0.D0,
/// . 6.D0, 6.D0, 6.D0, 0.D0,
/// . 6.D0, 6.D0, 0.D0, 0.D0,
/// . 6.D0, 0.D0, 0.D0, 0.D0 /
///
/// DATA SETB / 2.D0, 0.D0, 0.D0, 0.D0,
/// . -3.D0, 0.D0, 0.D0, 0.D0,
/// . 0.D0, 7.D0, 0.D0, 0.D0,
/// . 0.D0, 0.D0, 9.D0, 0.D0 /
///
/// C
/// C Calculate the projection
/// C
/// DO I=1, SETSIZ
///
/// CALL VPROJG ( SETA(1,I), SETB(1,I), NDIM, PVEC )
/// WRITE(*,'(A,4F5.1)') 'Vector A : ',
/// . ( SETA(M,I), M = 1, NDIM )
/// WRITE(*,'(A,4F5.1)') 'Vector B : ',
/// . ( SETB(M,I), M = 1, NDIM )
/// WRITE(*,'(A,4F5.1)') 'Projection: ', PVEC
/// WRITE(*,*)
///
/// END DO
///
/// END
///
///
/// When this program was executed on a Mac/Intel/gfortran/64-bit
/// platform, the output was:
///
///
/// Vector A : 6.0 6.0 6.0 0.0
/// Vector B : 2.0 0.0 0.0 0.0
/// Projection: 6.0 0.0 0.0 0.0
///
/// Vector A : 6.0 6.0 6.0 0.0
/// Vector B : -3.0 0.0 0.0 0.0
/// Projection: 6.0 -0.0 -0.0 -0.0
///
/// Vector A : 6.0 6.0 0.0 0.0
/// Vector B : 0.0 7.0 0.0 0.0
/// Projection: 0.0 6.0 0.0 0.0
///
/// Vector A : 6.0 0.0 0.0 0.0
/// Vector B : 0.0 0.0 9.0 0.0
/// Projection: 0.0 0.0 0.0 0.0
/// ```
///
/// # Restrictions
///
/// ```text
/// 1) No error detection or recovery schemes are incorporated into
/// this routine except to insure that no attempt is made to
/// divide by zero. Thus, the user is required to make sure that
/// the vectors A and B are such that no floating point overflow
/// will occur when the dot products are calculated.
/// ```
///
/// # Literature References
///
/// ```text
/// [1] G. Thomas and R. Finney, "Calculus and Analytic Geometry,"
/// 7th Edition, Addison Wesley, 1988.
/// ```
///
/// # Author and Institution
///
/// ```text
/// N.J. Bachman (JPL)
/// J. Diaz del Rio (ODC Space)
/// H.A. Neilan (JPL)
/// W.L. Taber (JPL)
/// E.D. Wright (JPL)
/// ```
///
/// # Version
///
/// ```text
/// - SPICELIB Version 1.1.0, 26-OCT-2021 (JDR)
///
/// Added IMPLICIT NONE statement.
///
/// Edited the header to comply with NAIF standard. Corrected math
/// expression in $Particulars section. Removed unnecessary
/// $Revisions section.
///
/// Added complete code example to $Examples section based on
/// existing example.
///
/// - SPICELIB Version 1.0.3, 23-APR-2010 (NJB)
///
/// Header correction: assertions that the output
/// can overwrite the input have been removed.
///
/// - SPICELIB Version 1.0.2, 22-AUG-2001 (EDW)
///
/// Corrected ENDIF to END IF.
///
/// - SPICELIB Version 1.0.1, 10-MAR-1992 (WLT)
///
/// Comment section for permuted index source lines was added
/// following the header.
///
/// - SPICELIB Version 1.0.0, 31-JAN-1990 (WLT) (HAN) (NJB)
/// ```
pub fn vprojg(a: &[f64], b: &[f64], ndim: i32, p: &mut [f64]) {
VPROJG(a, b, ndim, p);
}
//$Procedure VPROJG ( Vector projection, general dimension )
pub fn VPROJG(A: &[f64], B: &[f64], NDIM: i32, P: &mut [f64]) {
let A = DummyArray::new(A, 1..=NDIM);
let B = DummyArray::new(B, 1..=NDIM);
let mut P = DummyArrayMut::new(P, 1..=NDIM);
let mut ADOTB: f64 = 0.0;
let mut BDOTB: f64 = 0.0;
let mut SCALE: f64 = 0.0;
//
// SPICELIB functions
//
//
// Local variables
//
ADOTB = VDOTG(A.as_slice(), B.as_slice(), NDIM);
BDOTB = VDOTG(B.as_slice(), B.as_slice(), NDIM);
if (BDOTB == 0.0) {
SCALE = 0.0;
} else {
SCALE = (ADOTB / BDOTB);
}
VSCLG(SCALE, B.as_slice(), NDIM, P.as_slice_mut());
}