From: Rushforth, Peter <prushfor@NRCan.gc.ca>

Date: Wed, 17 Sep 2008 15:26:17 -0400

Message-ID: <E3942D3EB127854BBBC18511759DD0030135493A@S0-OTT-X2.nrn.nrcan.gc.ca>

To: <www-math@w3.org>

Date: Wed, 17 Sep 2008 15:26:17 -0400

Message-ID: <E3942D3EB127854BBBC18511759DD0030135493A@S0-OTT-X2.nrn.nrcan.gc.ca>

To: <www-math@w3.org>

Greetings, Not sure if this list will accept rich email like this, but I'll give it a try. I'm trying to encode the equations below for Lambert Conformal Conic (2 std parallels) into content markup, and thence to use xslt to generate equivalent xslt functions. I have taken a stab at the content markup, but I'm not sure if I'm on the right track, could you give me a couple of pointers please. First, the equations for easting and northing are quite deeply nested definitions. I am wondering if one should try to define csymbol elements for each sub-element, and then reference those csymbols where appropriate. Or perhasp those re-usable pieces should be fn elements (although this seems to be deprecated?). You can see that there are effectively function definitions which could be re-used, for example the definition of t can be used to calculate t1, t2, tF and t by substituting various values of phi. Likewise for m, n, and F. Here's what I'm trying to encode: Easting, E = EF + r sin q Northing, N = NF + rF - r cos q where m = cosj/(1 - e2sin2j) 0.5 for m1, j1, and m2, j2 where j1 and j2 are the latitudes of the standard parallels t = tan(p/4 - j/2)/[(1 - e sinj)/(1 + e sinj)] e/2 for t1, t2, tF and t using j1, j2, jF and j respectively n = (ln m1 - ln m2)/(ln t1 - ln t2) F = m1/(nt1n) r = a F tn for rF and r, where rF is the radius of the parallel of latitude of the false origin q = n(l - lF) The reverse formulas to derive the latitude and longitude of a point from its Easting and Northing values are: j = p/2 - 2atan{t'[(1 - esinj)/(1 + esinj)]e/2} l = q'/n +lF where r' = ±{(E - EF) 2 + [rF - (N - NF)] 2}0.5, taking the sign of n t' = (r'/(aF))1/n q' = atan [(E - EF)/(rF - (N - NF))] and n, F, and rF are derived as for the forward calculation. Here's the result for the Easting and Northing, respectively, haven't tried going too much further yet, as I think I might be going down the wrong track with declare?: I can say that I've tested what this looks like in firefox with appropriate fonts installed etc., and it doesn't look like I'm doing anything right. I use the stylesheets referenced by the http://www.w3.org/Math/XSL/csmall2.xml document to transform my content to presentation and it doesn't look like I'm capturing what I want to. <math xmlns="http://www.w3.org/1998/Math/MathML"> <declare type="function" nargs="2"> <apply> <plus/> <ci> <msub> <mi>E</mi> <mi>F</mi> </msub> </ci> <apply> <times/> <ci>r</ci> <apply> <sin/> <ci>theta</ci> </apply> </apply> </apply> <apply/> </declare> <declare type="function" nargs="2"> <apply> <plus/> <ci> <msub> <mi>N</mi> <mi>F</mi> </msub> </ci> <apply> <minus/> <ci> <msub> <mi>r</mi> <mi>F</mi> </msub> </ci> <apply> <times/> <ci>r</ci> <apply> <cos/> <ci>theta</ci> </apply> </apply> </apply> </apply> </declare> </math> Thanks for any advice. Cheers, PeterReceived on Wednesday, 17 September 2008 19:27:01 UTC

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