interpolate.h

Functions

static inline void comp_sum(real num, real *sum, real *compCoeff)

Compute the sum of two real numbers with a compensated summation.

Parameters:

• num – [in] Number to add to the sum.

• sum – [inout] Sum of the numbers.

• compCoeff – [inout] Compensation coefficient.

void approx_xInteg_math(const std::vector<real> &xInteg0, const std::vector<real> &accInteg0, const real &dt, const real &h, const std::vector<real> &b, const size_t &dim, const size_t starti, const size_t startb, const size_t &iterStep, std::vector<real> &xIntegNext, std::vector<real> &xIntegCompCoeffs)

Evaluate the Gauss-Radau polynomial.

Parameters:

• xInteg0 – [in] Initial state vector.

• accInteg0 – [in] Initial acceleration vector.

• dt – [in] Integration time step.

• h – [in] Fraction of the time step to use for the approximation.

• b – [in] Interpolation coefficients for the Gauss-Radau polynomial.

• dim – [in] Dimension of the system (number of 2nd derivatives).

• starti – [in] Starting index of the state vector to approximate.

• startb – [in] Starting index of the interpolation coefficients.

• iterStep – [in] Number of derivatives to evaluate.

• xIntegNext – [out] Approximated state vector.

• xIntegCompCoeffs – [out] Compensation coefficients.

void approx_xInteg(const std::vector<real> &xInteg0, const std::vector<real> &accInteg0, const real &dt, const real &h, const std::vector<real> &b, const size_t &dim, const std::vector<IntegBody> &integBodies, std::vector<real> &xIntegNext, std::vector<real> &xIntegCompCoeffs)

Use the Gauss-Radau polynomial to approximate the integral of the acceleration.

Parameters:

• xInteg0 – [in] Initial state vector.

• accInteg0 – [in] Initial acceleration vector.

• dt – [in] Integration time step.

• h – [in] Fraction of the time step to use for the approximation.

• b – [in] Interpolation coefficients for the Gauss-Radau polynomial.

• dim – [in] Dimension of the system (number of 2nd derivatives).

• integBodies – [in] List of integrated bodies in the PropSimulation.

• xIntegNext – [out] Approximated state vector.

• xIntegCompCoeffs – [out] Compensation coefficients.

void interpolate_on_the_fly(PropSimulation *propSim, const real &t, const real &dt)

Interpolate the integrator state for the time step that was just completed.

Parameters:

• propSim – [in] PropSimulation object for the integration.

• t – [in] Time at the beginning of the time step.

• dt – [in] Completed time step size.

void get_interpIdxInWindow(const PropSimulation *propSim, const real &tWindowStart, const real &tNext, const bool &forwardProp, const bool &backwardProp, bool &interpIdxInWindow)

Determine whether the next interpolation index is within the window of the time step that was just completed.

Parameters:

• propSim – [in] PropSimulation object for the integration.

• tWindowStart – [in] Start time of the interpolation window.

• tNext – [in] Time of the next interpolation.

• forwardProp – [in] Flag to indicate forward integration.

• backwardProp – [in] Flag to indicate backward integration.

• interpIdxInWindow – [out] Flag to indicate whether the next interpolation index is within the window.

void get_lightTime_and_xRelative(PropSimulation *propSim, const size_t interpIdx, const real tInterpGeom, const std::vector<real> &xInterpGeom, std::vector<real> &lightTime, std::vector<real> &xInterpApparent)

Compute the light time and apparent position of the target body.

Parameters:

• propSim – [in] PropSimulation object for the integration.

• interpIdx – [in] Index of the next interpolation time.

• tInterpGeom – [in] Time to interpolate to.

• xInterpGeom – [in] Geometric state vector of the target body.

• lightTime – [out] Light time to the target body.

• xInterpApparent – [out] Apparent state vector of the target body.

void get_lightTimeOneBody(PropSimulation *propSim, const size_t &i, const real tInterpGeom, std::vector<real> xInterpGeom, std::vector<real> xObserver, const bool bouncePointAtCenterOfMass, real &lightTimeOneBody)

Compute the light time to the target body.

Parameters:

• propSim – [in] PropSimulation object for the integration.

• i – [in] Index of the target body.

• tInterpGeom – [in] Time to interpolate to.

• xInterpGeom – [in] Geometric state vector of the target body.

• xObserver – [in] State vector of the observer.

• bouncePointAtCenterOfMass – [in] Flag to indicate whether the bounce point is at the center of mass (as opposed to leading edge).

• lightTimeOneBody – [out] Light time to the target body.