• Re: angle type

    From Tristan Wibberley@3:633/10 to All on Fri Jun 12 04:40:57 2026
    On 20/05/2026 08:50, Lawrence D?Oliveiro wrote:
    On Wed, 20 May 2026 07:29:06 +0200, fir wrote:

    i wonder if it would be not good in programing and on cpu level
    having a type for angles

    it seem ofr sure ot should be form 0.00 to 0.9999999.. so its kinda
    float

    Radians are the most natural unit for most trig calculations.

    <https://gitlab.com/ldo/python_topics_notebooks/-/blob/master/Angle%20Units.ipynb?ref_type=heads>

    also quarter turns, i.e. hundredgrads - it "turns" out (ahaha, pun
    intended) that the "grad" mode on a scientific calculator is useful
    after all.

    They're meaningful computationally, especially in a twos-complement unsigned-integer fixed-point representation that overflows gracefully to
    0 at 4 (or to -2 at 2 if you choose to see it that way). unsigned and
    signed representations are equivalent in this case and there's elegant mathematics related to the indexing of the imaginary unit and base 2 logarithms.

    --
    Tristan Wibberley

    The message body is Copyright (C) 2026 Tristan Wibberley except
    citations and quotations noted. All Rights Reserved except that you may,
    of course, cite it academically giving credit to me, distribute it
    verbatim as part of a usenet system or its archives, and use it to
    promote my greatness and general superiority without misrepresentation
    of my opinions other than my opinion of my greatness and general
    superiority which you _may_ misrepresent. You definitely MAY NOT train
    any production AI system with it but you may train experimental AI that
    will only be used for evaluation of the AI methods it implements.

    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Tristan Wibberley@3:633/10 to All on Fri Jun 12 04:47:00 2026
    On 21/05/2026 02:23, Lawrence D?Oliveiro wrote:
    On Wed, 20 May 2026 10:03:20 +0200, fir wrote:

    Lawrence D?Oliveiro pisze:

    Radians are the most natural unit for most trig calculations.

    i dont know in fact but i dont think so - imo 0...1 has more sense

    In radians,

    sin x ? x as x ? 0

    But only in radians.

    actually sinx -> x as x -> 0

    and that's true of any linear function of x defined close to x=0, so
    also for degrees and grads.

    ITYM "sin x is approximately = x for small x" which is only gesturally
    useful because it doesn't say /how/ approximate for /how/ small - in
    which we find that we can use degrees as long as we multiply our
    approximation threshold when we divide our size threshold.


    --
    Tristan Wibberley

    The message body is Copyright (C) 2026 Tristan Wibberley except
    citations and quotations noted. All Rights Reserved except that you may,
    of course, cite it academically giving credit to me, distribute it
    verbatim as part of a usenet system or its archives, and use it to
    promote my greatness and general superiority without misrepresentation
    of my opinions other than my opinion of my greatness and general
    superiority which you _may_ misrepresent. You definitely MAY NOT train
    any production AI system with it but you may train experimental AI that
    will only be used for evaluation of the AI methods it implements.

    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Tristan Wibberley@3:633/10 to All on Fri Jun 12 05:01:06 2026
    On 21/05/2026 22:16, fir wrote:
    fir pisze:

    Summary:
    For the whole software ecosystem:

    essentially negligible.

    For phase-heavy kernels:

    potentially very noticeable.

    For DSP/audio/simulation:

    a genuinely meaningful idea.

    Historically:

    it could have been quite powerful.

    Mathematically:

    it is a very elegant concept.

    Architecturally:

    the problem is too niche for mainstream x64 ISA support.

    sorry for talkin with ai (i uset to talk with myself (its a joke, i was
    not talking with myself really just adding thoughts) so now i can talk
    withm myself and ai ;c but as this group is not big and in some topic is
    not a biger chance for indepth discussion i can post some ai answers
    which in turn trigges many f smaller potential points of dicussion if
    someone is interested (and if no may skip/ignore..still for me most
    important is if subject is good and thoughts are reasonable)

    A word of caution. The AI is talking as if you've found something new.
    It's actually completely ordinary and well-worn.

    But when you need floating-point (and many fields /do/ because of it's properties of varying levels of approximation), you're not just going to
    do the work yourself - it's actually pretty hard, so it needs to be in
    the language's library for you, and then you may as well get it in
    radians because the maths references you use are in radians and who
    needs another problem added to their specialism when you're working with approximations anyway?

    --
    Tristan Wibberley

    The message body is Copyright (C) 2026 Tristan Wibberley except
    citations and quotations noted. All Rights Reserved except that you may,
    of course, cite it academically giving credit to me, distribute it
    verbatim as part of a usenet system or its archives, and use it to
    promote my greatness and general superiority without misrepresentation
    of my opinions other than my opinion of my greatness and general
    superiority which you _may_ misrepresent. You definitely MAY NOT train
    any production AI system with it but you may train experimental AI that
    will only be used for evaluation of the AI methods it implements.

    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Tristan Wibberley@3:633/10 to All on Fri Jun 12 05:07:07 2026
    On 22/05/2026 12:54, fir wrote:
    radians suck (and should be thrown out both c and math)

    You actually /can't/ do that without throwing out maths. They will
    always appear.


    --
    Tristan Wibberley

    The message body is Copyright (C) 2026 Tristan Wibberley except
    citations and quotations noted. All Rights Reserved except that you may,
    of course, cite it academically giving credit to me, distribute it
    verbatim as part of a usenet system or its archives, and use it to
    promote my greatness and general superiority without misrepresentation
    of my opinions other than my opinion of my greatness and general
    superiority which you _may_ misrepresent. You definitely MAY NOT train
    any production AI system with it but you may train experimental AI that
    will only be used for evaluation of the AI methods it implements.

    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Chris M. Thomasson@3:633/10 to All on Thu Jun 11 21:21:11 2026
    On 5/22/2026 9:31 PM, Lawrence D?Oliveiro wrote:
    On Fri, 22 May 2026 15:20:08 -0700, Chris M. Thomasson wrote:

    I use radians all the damn time!

    Radians are the most natural units for most trig calculations.

    I use radians all the time. Want 90 degrees? PI / 2, simple. :^)



    But I have no problem with supporting different angle units. Let the
    user input angles in whatever units they want, and get back answers in whatever units they want. Internally, all angles get converted to
    radians, the calculations are done, and the results converted back
    again.

    What annoys me just a bit is seeing these little functions like
    ?degrees to radians? and ?radians to degrees? -- so you need two
    conversion functions (converting to and from radians) for every angle
    unit you want to support.

    It?s simpler to just offer a single conversion factor, which can be
    used like this:

    ®angle-in-units-X¯ ? ®conversion-factor-for-units-X¯ ? ®angle-in-radians¯

    and going the other way:

    ®angle-in-radians¯ ö ®conversion-factor-for-units-X¯ ? ®angle-in-units-X¯

    So for example if you want angles in degrees, then the conversion
    factor is ã/180; if you want to work in units of full circles, then
    the conversion factor is 2ã. All nice and simple, and scalable, too.


    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Tristan Wibberley@3:633/10 to All on Fri Jun 12 05:47:19 2026
    On 24/05/2026 23:53, Lawrence D?Oliveiro wrote:
    On Sun, 24 May 2026 15:57:38 +0800, makendo wrote:

    (Irrational numbers are discovered around 2,500 years ago.)

    The Pythagoreans were horrified by the discovery. They saw it as some
    kind of defect in the perfection of mathematics, and therefore of
    reality, itself.

    They were conceited!

    They tried to cover it up. One story is that the mathematician
    Hippasus was killed to keep him from revealing the secret.

    I wonder to which powerful lord they'd made promises about their methods
    which now they knew couldn't be kept?

    --
    Tristan Wibberley

    The message body is Copyright (C) 2026 Tristan Wibberley except
    citations and quotations noted. All Rights Reserved except that you may,
    of course, cite it academically giving credit to me, distribute it
    verbatim as part of a usenet system or its archives, and use it to
    promote my greatness and general superiority without misrepresentation
    of my opinions other than my opinion of my greatness and general
    superiority which you _may_ misrepresent. You definitely MAY NOT train
    any production AI system with it but you may train experimental AI that
    will only be used for evaluation of the AI methods it implements.

    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Chris M. Thomasson@3:633/10 to All on Thu Jun 11 23:50:09 2026
    On 5/20/2026 6:23 PM, Lawrence D?Oliveiro wrote:
    On Wed, 20 May 2026 10:03:20 +0200, fir wrote:

    Lawrence D?Oliveiro pisze:

    Radians are the most natural unit for most trig calculations.

    i dont know in fact but i dont think so - imo 0...1 has more sense

    In radians,

    sin x ? x as x ? 0

    But only in radians.

    from memory:

    cos(0) = 1, sin(0) = 0
    cos(PI / 2) = 0, sin(PI / 2) = 1
    cos(PI) = -1, sin(PI) = 0
    ...

    Around we go. :^)


    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From James Kuyper@3:633/10 to All on Fri Jun 12 07:15:13 2026
    On 2026-06-11 23:47, Tristan Wibberley wrote:
    On 21/05/2026 02:23, Lawrence D?Oliveiro wrote:
    ...
    In radians,

    sin x ? x as x ? 0

    But only in radians.

    actually sinx -> x as x -> 0

    and that's true of any linear function of x defined close to x=0, so
    also for degrees and grads.

    ITYM "sin x is approximately = x for small x" which is only gesturally
    useful because it doesn't say /how/ approximate for /how/ small - in
    which we find that we can use degrees as long as we multiply our approximation threshold when we divide our size threshold.

    sin x = x - x^3/3! + ... is true only when x is in radians. cos x = 1 =
    x^2/2! + ... is also true only in radians. There's similar expansions
    for all of the trig functions, and radians are favored by those
    forumulas because they are simplest in those units.

    sin x = (e^{ix} - e^(-ix))/2, and the similar formulas for the other
    trig functions get more complicated when x is in radians.

    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From David Brown@3:633/10 to All on Fri Jun 12 13:36:26 2026
    On 12/06/2026 13:15, James Kuyper wrote:
    On 2026-06-11 23:47, Tristan Wibberley wrote:
    On 21/05/2026 02:23, Lawrence D?Oliveiro wrote:
    ...
    In radians,

    sin x ? x as x ? 0

    But only in radians.

    actually sinx -> x as x -> 0

    and that's true of any linear function of x defined close to x=0, so
    also for degrees and grads.

    ITYM "sin x is approximately = x for small x" which is only gesturally
    useful because it doesn't say /how/ approximate for /how/ small - in
    which we find that we can use degrees as long as we multiply our
    approximation threshold when we divide our size threshold.

    sin x = x - x^3/3! + ... is true only when x is in radians. cos x = 1 = x^2/2! + ... is also true only in radians. There's similar expansions
    for all of the trig functions, and radians are favored by those
    forumulas because they are simplest in those units.


    True.

    An angle "x" in radians is "(x . 180 / ã)" degrees, so if you have an
    angle "y" in degrees, the "rad" function to convert it to radians is
    rad(y) := y.ã / 180.

    Thus for y in degrees,

    sin_degrees(y) = sin rad(y) = y.ã / 180 - y?.ã?/3!.180? + ...


    sin x = (e^{ix} - e^(-ix))/2, and the similar formulas for the other
    trig functions get more complicated when x is in radians.

    I think you meant "when x is /not/ in radians". But that is not
    correct. This formula is unchanged, as are things like

    sin(à + ?) = sin(à).cos(?) + cos(à).sin(?)

    The scale factor hits you when differentiating or integrating, such as
    for the Taylor series.



    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From fir@3:633/10 to All on Fri Jun 12 13:39:45 2026
    Tristan Wibberley pisze:
    On 21/05/2026 22:16, fir wrote:
    fir pisze:

    Summary:
    For the whole software ecosystem:

    essentially negligible.

    For phase-heavy kernels:

    potentially very noticeable.

    For DSP/audio/simulation:

    a genuinely meaningful idea.

    Historically:

    it could have been quite powerful.

    Mathematically:

    it is a very elegant concept.

    Architecturally:

    the problem is too niche for mainstream x64 ISA support.

    sorry for talkin with ai (i uset to talk with myself (its a joke, i was
    not talking with myself really just adding thoughts) so now i can talk
    withm myself and ai ;c but as this group is not big and in some topic is
    not a biger chance for indepth discussion i can post some ai answers
    which in turn trigges many f smaller potential points of dicussion if
    someone is interested (and if no may skip/ignore..still for me most
    important is if subject is good and thoughts are reasonable)

    A word of caution. The AI is talking as if you've found something new.
    It's actually completely ordinary and well-worn.

    But when you need floating-point (and many fields /do/ because of it's properties of varying levels of approximation), you're not just going to
    do the work yourself - it's actually pretty hard, so it needs to be in
    the language's library for you, and then you may as well get it in
    radians because the maths references you use are in radians and who
    needs another problem added to their specialism when you're working with approximations anyway?


    im not exactly say i say something new - (this new depends on area, i
    would say, in some areas it may be new in some not etc, its complex
    thing) i more like say this is a logical conclusion

    (and if this is a logical conclusion its weird its not used)

    (but i dont have mindset now to go again into it, as i simply changed
    my topic of focus and it would need to ao a bit deeper in it again)

    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From David Brown@3:633/10 to All on Fri Jun 12 13:50:05 2026
    On 12/06/2026 05:47, Tristan Wibberley wrote:
    On 21/05/2026 02:23, Lawrence D?Oliveiro wrote:
    On Wed, 20 May 2026 10:03:20 +0200, fir wrote:

    Lawrence D?Oliveiro pisze:

    Radians are the most natural unit for most trig calculations.

    i dont know in fact but i dont think so - imo 0...1 has more sense

    In radians,

    sin x ? x as x ? 0

    But only in radians.

    actually sinx -> x as x -> 0

    and that's true of any linear function of x defined close to x=0, so
    also for degrees and grads.

    No, it is not. In degrees, sin x ? x.ã / 180 as x ? 0. If you have a function "f" such that "f(x)" tends to "x" as "x" tends to 0, and a
    function "g" continuous on the appropriate domain, then "f(g(x))" tends
    to "g(x)" as "g(x)" tends to 0. For "g(x)" of the form "k.x" - a simple scaling, such as degrees to radians - then "f(k.x)" tends to "k.x" as
    "x" tends to 0. (Note that it is more complicated for general linear functions, which have an additive constant as well as a scaling constant.)



    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From fir@3:633/10 to All on Fri Jun 12 14:31:35 2026
    Tristan Wibberley pisze:
    On 20/05/2026 08:50, Lawrence D?Oliveiro wrote:
    On Wed, 20 May 2026 07:29:06 +0200, fir wrote:

    i wonder if it would be not good in programing and on cpu level
    having a type for angles

    it seem ofr sure ot should be form 0.00 to 0.9999999.. so its kinda
    float

    Radians are the most natural unit for most trig calculations.

    <https://gitlab.com/ldo/python_topics_notebooks/-/blob/master/Angle%20Units.ipynb?ref_type=heads>

    also quarter turns, i.e. hundredgrads - it "turns" out (ahaha, pun
    intended) that the "grad" mode on a scientific calculator is useful
    after all.

    They're meaningful computationally, especially in a twos-complement unsigned-integer fixed-point representation that overflows gracefully to
    0 at 4 (or to -2 at 2 if you choose to see it that way). unsigned and
    signed representations are equivalent in this case and there's elegant mathematics related to the indexing of the imaginary unit and base 2 logarithms.


    ye i also thought that thise e^x are not so friendly to computing as 2^x
    (but now i m not in mood to go into that to much)

    those numbers pi and e come from this sum(z^n/n!)
    quite strightforwardly though, and as i said im not so sure if i should
    like tehem as they are not quite computational firendly probbaly
    (but im not sure how much that yan be avoided mathematically of computationally - and right now im not in a mood to dwell into that)


    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Tristan Wibberley@3:633/10 to All on Fri Jun 12 17:25:29 2026
    On 12/06/2026 05:50, Stefan Ram wrote:
    Tristan Wibberley <tristan.wibberley+netnews2@alumni.manchester.ac.uk> wrote or quoted:
    ITYM "sin x is approximately = x for small x" which is only gesturally
    useful because it doesn't say /how/ approximate for /how/ small - in

    A more precise wording might be:

    The function f( x )=x is the best affine-linear approximation to
    sine at 0 in the sense that it matches the function value and first
    derivative at that point (the first-order Taylor polynomial).

    , but we also could use wordings that do not refer to derivatives,

    The function f( x )=x is the best affine-linear approximation to
    sine at 0 in the sense that the error, sin( x )- f( x ), vanishes
    strictly faster than linearly as x approaches 0.

    , or,

    The function f( x )=x is the best linear approximation to sine
    at 0 in the sense that it provides the tightest possible linear
    upper bound for sine when x > 0 in a neighborhood of 0.



    oooh, you give me CHILLS!

    --
    Tristan Wibberley

    The message body is Copyright (C) 2026 Tristan Wibberley except
    citations and quotations noted. All Rights Reserved except that you may,
    of course, cite it academically giving credit to me, distribute it
    verbatim as part of a usenet system or its archives, and use it to
    promote my greatness and general superiority without misrepresentation
    of my opinions other than my opinion of my greatness and general
    superiority which you _may_ misrepresent. You definitely MAY NOT train
    any production AI system with it but you may train experimental AI that
    will only be used for evaluation of the AI methods it implements.

    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From David Brown@3:633/10 to All on Fri Jun 12 18:47:15 2026
    On 12/06/2026 18:25, Tristan Wibberley wrote:
    On 12/06/2026 05:50, Stefan Ram wrote:
    Tristan Wibberley <tristan.wibberley+netnews2@alumni.manchester.ac.uk> wrote or quoted:
    ITYM "sin x is approximately = x for small x" which is only gesturally
    useful because it doesn't say /how/ approximate for /how/ small - in

    A more precise wording might be:

    The function f( x )=x is the best affine-linear approximation to
    sine at 0 in the sense that it matches the function value and first
    derivative at that point (the first-order Taylor polynomial).

    , but we also could use wordings that do not refer to derivatives,

    The function f( x )=x is the best affine-linear approximation to
    sine at 0 in the sense that the error, sin( x )- f( x ), vanishes
    strictly faster than linearly as x approaches 0.

    , or,

    The function f( x )=x is the best linear approximation to sine
    at 0 in the sense that it provides the tightest possible linear
    upper bound for sine when x > 0 in a neighborhood of 0.



    oooh, you give me CHILLS!


    Or you could just say, as you did, that sin x ? x as x ? 0. Stefan's
    first and third alternatives are not more precise - they just sound more profound, and are directly derivable from from your wording. His second alternative is, I think at first glance, untrue.


    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Keith Thompson@3:633/10 to All on Fri Jun 12 11:45:50 2026
    David Brown <david.brown@hesbynett.no> writes:
    [...]
    Or you could just say, as you did, that sin x ? x as x ? 0. Stefan's
    first and third alternatives are not more precise - they just sound
    more profound, and are directly derivable from from your wording. His
    second alternative is, I think at first glance, untrue.

    But that's true even if x is expressed in radians or degrees, since
    sin(x) is continuous and sin(0)=0.

    What's more interesting and useful is that sin x / x ? 1 as x ? 0.

    --
    Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
    void Void(void) { Void(); } /* The recursive call of the void */

    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Keith Thompson@3:633/10 to All on Fri Jun 12 11:49:52 2026
    David Brown <david.brown@hesbynett.no> writes:
    On 12/06/2026 05:47, Tristan Wibberley wrote:
    On 21/05/2026 02:23, Lawrence D?Oliveiro wrote:
    On Wed, 20 May 2026 10:03:20 +0200, fir wrote:
    Lawrence D?Oliveiro pisze:
    Radians are the most natural unit for most trig calculations.

    i dont know in fact but i dont think so - imo 0...1 has more sense

    In radians,

    sin x ? x as x ? 0

    But only in radians.
    actually sinx -> x as x -> 0
    and that's true of any linear function of x defined close to x=0, so
    also for degrees and grads.

    No, it is not.
    [...]

    Yes, it is.

    I think the ambiguity of the ? notation might be throwing you off.

    What is the limit as x approaches 0 of sin x? The limit is 0 whether
    x is expressed in radians, degrees, or anything else.

    --
    Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
    void Void(void) { Void(); } /* The recursive call of the void */

    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Chris M. Thomasson@3:633/10 to All on Fri Jun 12 12:53:04 2026
    On 6/12/2026 5:31 AM, fir wrote:
    Tristan Wibberley pisze:
    On 20/05/2026 08:50, Lawrence D?Oliveiro wrote:
    On Wed, 20 May 2026 07:29:06 +0200, fir wrote:

    i wonder if it would be not good in programing and on cpu level
    having a type for angles

    it seem ofr sure ot should be form 0.00 to 0.9999999.. so its kinda
    float

    Radians are the most natural unit for most trig calculations.

    <https://gitlab.com/ldo/python_topics_notebooks/-/blob/master/
    Angle%20Units.ipynb?ref_type=heads>

    also quarter turns, i.e. hundredgrads - it "turns" out (ahaha, pun
    intended) that the "grad" mode on a scientific calculator is useful
    after all.

    They're meaningful computationally, especially in a twos-complement
    unsigned-integer fixed-point representation that overflows gracefully to
    0 at 4 (or to -2 at 2 if you choose to see it that way). unsigned and
    signed representations are equivalent in this case and there's elegant
    mathematics related to the indexing of the imaginary unit and base 2
    logarithms.


    ye i also thought that thise e^x are not so friendly to computing as 2^x
    (but now i m not in mood to go into that to much)

    those numbers pi and e come from this sum(z^n/n!)
    quite strightforwardly though, and as i said im not so sure if i should
    like tehem as they are not quite computational firendly probbaly
    (but im not sure how much that yan be avoided mathematically of computationally - and right now im not in a mood to dwell into that)


    Making a circle using e? Not all that hard.

    Say:

    namespace ct_misc_plot
    {
    void
    manifest(
    ct::plot::cairo::plot_2d& scene
    ) {
    std::cout << "ct_misc_plot::manifest()\n";

    ct_complex e = { std::exp(1.0f), 0 };

    unsigned long n = 10;

    float angle_base = CT_PI2 / n;

    for (unsigned long i = 0; i < n; ++i)
    {
    float angle = angle_base * i;

    ct_complex power = { 0, angle };
    ct_complex p0 = std::pow(e, power);

    scene.circle_filled({ p0.real(), p0.imag() }, .05,
    CT_RGBF(1, 0, 0));
    }
    }
    }

    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From David Brown@3:633/10 to All on Sat Jun 13 15:56:51 2026
    On 12/06/2026 20:49, Keith Thompson wrote:
    David Brown <david.brown@hesbynett.no> writes:
    On 12/06/2026 05:47, Tristan Wibberley wrote:
    On 21/05/2026 02:23, Lawrence D?Oliveiro wrote:
    On Wed, 20 May 2026 10:03:20 +0200, fir wrote:
    Lawrence D?Oliveiro pisze:
    Radians are the most natural unit for most trig calculations.

    i dont know in fact but i dont think so - imo 0...1 has more sense

    In radians,

    sin x ? x as x ? 0

    But only in radians.
    actually sinx -> x as x -> 0
    and that's true of any linear function of x defined close to x=0, so
    also for degrees and grads.

    No, it is not.
    [...]

    Yes, it is.

    I think the ambiguity of the ? notation might be throwing you off.

    No, it was not that - it was a brain fart from posting when too tired.
    Of course you (and others) are correct here.

    I was thinking too much that, for constant k (such as the scale factor
    for degrees), sin k.x tends to k.x as x tends to 0. This is, usually, a
    more useful and interesting result (as you noted, (sin x) / x tends to 1
    when sin is in radians, but not in other units).

    However, since the absolute value of (sin k.x - x) tends to (k.x - x) =
    (k - 1).x as x tends to 0, sin k.x also tends to x as x tends to 0.


    What is the limit as x approaches 0 of sin x? The limit is 0 whether
    x is expressed in radians, degrees, or anything else.




    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From David Brown@3:633/10 to All on Sat Jun 13 15:56:54 2026
    On 12/06/2026 20:45, Keith Thompson wrote:
    David Brown <david.brown@hesbynett.no> writes:
    [...]
    Or you could just say, as you did, that sin x ? x as x ? 0. Stefan's
    first and third alternatives are not more precise - they just sound
    more profound, and are directly derivable from from your wording. His
    second alternative is, I think at first glance, untrue.

    But that's true even if x is expressed in radians or degrees, since
    sin(x) is continuous and sin(0)=0.


    Yes - I was not thinking straight. (See my reply to your other post.)

    What's more interesting and useful is that sin x / x ? 1 as x ? 0.


    Indeed - though that one is only true in radians.


    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From James Kuyper@3:633/10 to All on Sat Jun 13 18:21:57 2026
    On 2026-06-12 07:36, David Brown wrote:
    On 12/06/2026 13:15, James Kuyper wrote:
    ...
    sin x = (e^{ix} - e^(-ix))/2, and the similar formulas for the other
    trig functions get more complicated when x is in radians.

    I think you meant "when x is /not/ in radians". ...

    Correct. Sorry.

    ... But that is not correct. This formula is unchanged, ...

    I don't believe that's the case. The key point is that e^(ix) does not
    get rescaled. It is simply "e" raised to that power - radians, grads,
    degrees, etc. mean nothing to it.

    ... as are things like

    sin(à + ?) = sin(à).cos(?) + cos(à).sin(?)

    That one is unchanged, because it involves trig functions, each of which
    is presumably also re-scaled to the appropriate angle measurement.



    --- PyGate Linux v1.5.16
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Lawrence D?Oliveiro@3:633/10 to All on Tue Jun 16 07:44:07 2026
    On Thu, 11 Jun 2026 23:50:09 -0700, Chris M. Thomasson wrote:

    cos(0) = 1, sin(0) = 0
    cos(PI / 2) = 0, sin(PI / 2) = 1
    cos(PI) = -1, sin(PI) = 0
    ...

    Continue subdividing the angles, and next step ... CORDIC!

    --- PyGate Linux v1.5.17
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)