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Incorrect results are generating with unit_vector() and magnitude() member functions of differential representations. #125

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rjnrohit opened this issue Apr 13, 2020 · 5 comments · May be fixed by #127
Open

Incorrect results are generating with unit_vector() and magnitude() member functions of differential representations. #125

rjnrohit opened this issue Apr 13, 2020 · 5 comments · May be fixed by #127

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@rjnrohit
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rjnrohit commented Apr 13, 2020 •
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User may instantiate a differential object as in the following way:

auto cart_rep_diff = make_cartesian_differential(34.9*meter/second,37.91*meters_per_second,490.1*centimeter/second);

and the generated results are as follows:

cart_rep_diff .magnitude() = 492.801

cart_rep_diff.unit_vector<decltype(cart_rep_diff)>() = Cartesian differential ( 0.0708196 m s^-1 , 0.0769275 m s^-1 , 0.994518 cm s^-1 )

But expected results are:
51.761 m s^-1 in case of magnitude
and for unit_vector is
Cartesian differential ( 0.674253 m s^-1 , 0.732405 m s^-1 , 0.0946852 cm s^-1 )
@rjnrohit rjnrohit changed the title Incorrect result generating with unit_vector() and magnitude() member functions of differential Representation. Incorrect result generating with unit_vector() and magnitude() member functions of differential representations. Apr 13, 2020
@rjnrohit
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Member functions unit_vector and magnitude need to be removed from header base_differential.hpp

@rjnrohit rjnrohit changed the title Incorrect result generating with unit_vector() and magnitude() member functions of differential representations. Incorrect results are generating with unit_vector() and magnitude() member functions of differential representations. Apr 13, 2020
@rjnrohit
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rjnrohit commented Apr 13, 2020 •
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I have updated base_differential.hpp in #127

@rjnrohit rjnrohit linked a pull request Apr 14, 2020 that will close this issue
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@Gopal-Dahale
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why is your expected result in m s^-1? it could also be cm s^-1. How to decide that?

@rjnrohit
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@Gopal-Dahale you can see here

astronomy/include/boost/astronomy/coordinate/arithmetic.hpp

Line 198 in 2a312f2

bg::set<1>(tempPoint, static_cast<XQuantity>(vector.get_y()).value());
. for the magnitude we're typecasting to XQuantity. It seems we expect magnitude in units of first coordinate quantity.

@Gopal-Dahale
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Well, I am able to convert the units but I had used the functions get_dx(), get_dy(), get_dz() for accessing the units whereas in the magnitude function in base_differential.hpp, cartesian_-differential is represented as a point (no units). Is there a way for me to get the units without using the getter methods as they are specific to different representations(cartesian, spherical etc).

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extend arithmetic functions to support differential quantities rjnrohit/astronomy
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@rjnrohit @Gopal-Dahale