Boost.Units - Can't figure out how to use it
Hi,
I've been reading the documentation for Boost.Units. I understand most of
what it is saying, but am still confused on how to do many things with this
library.
Most of the examples are using that test_system.hpp. Does this mean that you
actually have to explicitly define the units you want to use?
I am confused because I see the header files for the units I want to use,
e.g., light_year or astronomical_unit, but I can't figure out how to
actually use them. If I use boost::units::astronomical::light_second, it
cannot find it. I am able to use the SI units just fine, such as:
Quantitysi::length l = 4.0 * si::meters;
But beyond that, I'm lost.
I also don't know which headers I should include. I don't know if there's
one or two headers that include all the basics I would need, or if I have to
include each of them individually.
Here's a simple program I was trying to write just to test light_second, but
do not know how to make it work or which headers to include:
int main()
{
using namespace boost::units;
using namespace boost::units::astronomical;
using namespace std;
quantity
AMDG Brandon Olivares wrote:
I've been reading the documentation for Boost.Units. I understand most of what it is saying, but am still confused on how to do many things with this library.
Most of the examples are using that test_system.hpp. Does this mean that you actually have to explicitly define the units you want to use?
I am confused because I see the header files for the units I want to use, e.g., light_year or astronomical_unit, but I can't figure out how to actually use them. If I use boost::units::astronomical::light_second, it cannot find it. I am able to use the SI units just fine, such as:
Quantitysi::length l = 4.0 * si::meters;
But beyond that, I'm lost.
I also don't know which headers I should include. I don't know if there's one or two headers that include all the basics I would need, or if I have to include each of them individually.
There is no catch-all header.
Here's a simple program I was trying to write just to test light_second, but do not know how to make it work or which headers to include:
int main() { using namespace boost::units; using namespace boost::units::astronomical; using namespace std;
quantity
l1 = 4.0 * light_second; cout << "l1 = " << l1 << endl;
return 0; }
#include
Steven, Thanks a lot. I actually figured this out last night. I hadn't been paying attention to the difference between base units and units, and assumed light_seconds was a unit. I have a few other questions now though. It is able to do scaling of units I know, but let's say you want to use kilometer for instance. It appears you cannot have two length units under the same system (correct?), so would you have to create a new system just for that unit? More practically, I need to use most of the astronomical units, or at least light years, parsecs, and astronomical units. It seems I can't put them under the same system, so must I have a separate system for each of them, or am I missing something? Thanks, Brandon On 2009-12-23, Steven Watanabe wrote:
AMDG
Brandon Olivares wrote:
I've been reading the documentation for Boost.Units. I understand most of what it is saying, but am still confused on how to do many things with this library.
Most of the examples are using that test_system.hpp. Does this mean that you actually have to explicitly define the units you want to use?
I am confused because I see the header files for the units I want to use, e.g., light_year or astronomical_unit, but I can't figure out how to actually use them. If I use boost::units::astronomical::light_second, it cannot find it. I am able to use the SI units just fine, such as:
Quantitysi::length l = 4.0 * si::meters;
But beyond that, I'm lost.
I also don't know which headers I should include. I don't know if there's one or two headers that include all the basics I would need, or if I have to include each of them individually.
There is no catch-all header.
Here's a simple program I was trying to write just to test light_second, but do not know how to make it work or which headers to include:
int main() { using namespace boost::units; using namespace boost::units::astronomical; using namespace std;
quantity
l1 = 4.0 * light_second; cout << "l1 = " << l1 << endl;
return 0; }
#include
#include #include #include <iostream> typedef boost::units::astronomical::light_second_base_unit::unit_type light_second;
int main() { using namespace boost::units; using namespace boost::units::astronomical; using namespace std;
quantity
l1 = 4.0 * light_second(); cout << "l1 = " << l1 << endl;
return 0; }
In Christ, Steven Watanabe
_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users
-- Brandon www.creatorspiritus.com Blog and forum discussing living a Christ-centered life Follow me on Twitter: http://twitter.com/devbanana
AMDG Brandon Olivares wrote:
Thanks a lot. I actually figured this out last night. I hadn't been paying attention to the difference between base units and units, and assumed light_seconds was a unit.
I have a few other questions now though.
It is able to do scaling of units I know, but let's say you want to use kilometer for instance. It appears you cannot have two length units under the same system (correct?), so would you have to create a new system just for that unit?
More practically, I need to use most of the astronomical units, or at least light years, parsecs, and astronomical units. It seems I can't put them under the same system, so must I have a separate system for each of them, or am I missing something?
You can just use the ::unit_type typedef in each base unit, if you don't want to worry about systems. In Christ, Steven Watanabe
On 2009-12-23, Steven Watanabe wrote:
AMDG
Brandon Olivares wrote:
I have a few other questions now though.
It is able to do scaling of units I know, but let's say you want to use kilometer for instance. It appears you cannot have two length units under the same system (correct?), so would you have to create a new system just for that unit?
More practically, I need to use most of the astronomical units, or at least light years, parsecs, and astronomical units. It seems I can't put them under the same system, so must I have a separate system for each of them, or am I missing something?
You can just use the ::unit_type typedef in each base unit, if you don't want to worry about systems.
Thanks. Then may I ask what the use is for systems? When should one or the other be used, or what is the advantages of each? I'm sorry if my questions seem stupid, but I just started reading about this library yesterday. God bless, Brandon
In Christ, Steven Watanabe
_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users
-- Brandon www.creatorspiritus.com Blog and forum discussing living a Christ-centered life Follow me on Twitter: http://twitter.com/devbanana
On 2009-12-23, Steven Watanabe wrote:
AMDG
Brandon Olivares wrote:
I have a few other questions now though.
It is able to do scaling of units I know, but let's say you want to use kilometer for instance. It appears you cannot have two length units under the same system (correct?), so would you have to create a new system just for that unit?
More practically, I need to use most of the astronomical units, or at least light years, parsecs, and astronomical units. It seems I can't put them under the same system, so must I have a separate system for each of them, or am I missing something?
You can just use the ::unit_type typedef in each base unit, if you don't want to worry about systems.
I have one more question about unit_type vs. system.
If I want a unit composed of several base units, how would I do that if I
just use unit_type as you were suggesting?
For instance, right now I have something like the following, just for
testing.
#ifndef BOOST_UNITS_ASTRONOMICAL_LIGHT_SECOND_HPP
#define BOOST_UNITS_ASTRONOMICAL_LIGHT_SECOND_HPP
#include
In Christ, Steven Watanabe
_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users
-- Brandon www.creatorspiritus.com Blog and forum discussing living a Christ-centered life Follow me on Twitter: http://twitter.com/devbanana
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