/* Function to compute, phi4, the latitude for the inverse of the
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Polyconic projection.
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------------------------------------------------------------*/
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function phi4z (eccent,e0,e1,e2,e3,a,b,c,phi) {
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var sinphi, sin2ph, tanphi, ml, mlp, con1, con2, con3, dphi, i;
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phi = a;
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for (i = 1; i <= 15; i++) {
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sinphi = Math.sin(phi);
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tanphi = Math.tan(phi);
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c = tanphi * Math.sqrt (1.0 - eccent * sinphi * sinphi);
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sin2ph = Math.sin (2.0 * phi);
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/*
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ml = e0 * *phi - e1 * sin2ph + e2 * sin (4.0 * *phi);
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mlp = e0 - 2.0 * e1 * cos (2.0 * *phi) + 4.0 * e2 * cos (4.0 * *phi);
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*/
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ml = e0 * phi - e1 * sin2ph + e2 * Math.sin (4.0 * phi) - e3 * Math.sin (6.0 * phi);
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mlp = e0 - 2.0 * e1 * Math.cos (2.0 * phi) + 4.0 * e2 * Math.cos (4.0 * phi) - 6.0 * e3 * Math.cos (6.0 * phi);
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con1 = 2.0 * ml + c * (ml * ml + b) - 2.0 * a * (c * ml + 1.0);
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con2 = eccent * sin2ph * (ml * ml + b - 2.0 * a * ml) / (2.0 *c);
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con3 = 2.0 * (a - ml) * (c * mlp - 2.0 / sin2ph) - 2.0 * mlp;
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dphi = con1 / (con2 + con3);
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phi += dphi;
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if (Math.abs(dphi) <= .0000000001 ) return(phi);
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}
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Proj4js.reportError("phi4z: No convergence");
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return null;
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}
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/* Function to compute the constant e4 from the input of the eccentricity
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of the spheroid, x. This constant is used in the Polar Stereographic
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projection.
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--------------------------------------------------------------------*/
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function e4fn(x) {
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var con, com;
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con = 1.0 + x;
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com = 1.0 - x;
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return (Math.sqrt((Math.pow(con,con))*(Math.pow(com,com))));
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}
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/*******************************************************************************
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NAME POLYCONIC
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PURPOSE: Transforms input longitude and latitude to Easting and
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Northing for the Polyconic projection. The
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longitude and latitude must be in radians. The Easting
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and Northing values will be returned in meters.
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PROGRAMMER DATE
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---------- ----
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T. Mittan Mar, 1993
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ALGORITHM REFERENCES
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1. Snyder, John P., "Map Projections--A Working Manual", U.S. Geological
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Survey Professional Paper 1395 (Supersedes USGS Bulletin 1532), United
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State Government Printing Office, Washington D.C., 1987.
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2. Snyder, John P. and Voxland, Philip M., "An Album of Map Projections",
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U.S. Geological Survey Professional Paper 1453 , United State Government
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Printing Office, Washington D.C., 1989.
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*******************************************************************************/
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Proj4js.Proj.poly = {
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/* Initialize the POLYCONIC projection
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----------------------------------*/
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init: function() {
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var temp; /* temporary variable */
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if (this.lat0 == 0) this.lat0 = 90;//this.lat0 ca
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/* Place parameters in static storage for common use
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-------------------------------------------------*/
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this.temp = this.b / this.a;
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this.es = 1.0 - Math.pow(this.temp,2);// devait etre dans tmerc.js mais n y est pas donc je commente sinon retour de valeurs nulles
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this.e = Math.sqrt(this.es);
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this.e0 = Proj4js.common.e0fn(this.es);
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this.e1 = Proj4js.common.e1fn(this.es);
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this.e2 = Proj4js.common.e2fn(this.es);
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this.e3 = Proj4js.common.e3fn(this.es);
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this.ml0 = Proj4js.common.mlfn(this.e0, this.e1,this.e2, this.e3, this.lat0);//si que des zeros le calcul ne se fait pas
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//if (!this.ml0) {this.ml0=0;}
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},
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/* Polyconic forward equations--mapping lat,long to x,y
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---------------------------------------------------*/
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forward: function(p) {
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var sinphi, cosphi; /* sin and cos value */
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var al; /* temporary values */
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var c; /* temporary values */
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var con, ml; /* cone constant, small m */
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var ms; /* small m */
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var x,y;
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var lon=p.x;
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var lat=p.y;
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con = Proj4js.common.adjust_lon(lon - this.long0);
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if (Math.abs(lat) <= .0000001) {
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x = this.x0 + this.a * con;
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y = this.y0 - this.a * this.ml0;
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} else {
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sinphi = Math.sin(lat);
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cosphi = Math.cos(lat);
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ml = Proj4js.common.mlfn(this.e0, this.e1, this.e2, this.e3, lat);
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ms = Proj4js.common.msfnz(this.e,sinphi,cosphi);
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con = sinphi;
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x = this.x0 + this.a * ms * Math.sin(con)/sinphi;
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y = this.y0 + this.a * (ml - this.ml0 + ms * (1.0 - Math.cos(con))/sinphi);
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}
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p.x=x;
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p.y=y;
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return p;
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},
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/* Inverse equations
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-----------------*/
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inverse: function(p) {
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var sin_phi, cos_phi; /* sin and cos value */
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var al; /* temporary values */
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var b; /* temporary values */
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var c; /* temporary values */
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var con, ml; /* cone constant, small m */
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var iflg; /* error flag */
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var lon,lat;
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p.x -= this.x0;
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p.y -= this.y0;
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al = this.ml0 + p.y/this.a;
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iflg = 0;
|
|
if (Math.abs(al) <= .0000001) {
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lon = p.x/this.a + this.long0;
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lat = 0.0;
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} else {
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b = al * al + (p.x/this.a) * (p.x/this.a);
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iflg = phi4z(this.es,this.e0,this.e1,this.e2,this.e3,this.al,b,c,lat);
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if (iflg != 1) return(iflg);
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lon = Proj4js.common.adjust_lon((Proj4js.common.asinz(p.x * c / this.a) / Math.sin(lat)) + this.long0);
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}
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p.x=lon;
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p.y=lat;
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return p;
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}
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};
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