Back and forth Google WGS84 and STIF Lambert 2 Étendu, via Lambert 93

gistfile1.go

package main

import (
    "fmt"
	proj "github.com/pebbe/go-proj-4/proj"
	"math"
)

type Poi struct {
	name            string
	x, y, lat, long float64
}

func main() {

	pois := []Poi{
		{"Bonne-Nouvelle", 600880.000000, 2430251.000000, 48.87052, 2.34880},
		{"Invalides", 598395.000000, 2429196.000000, 48.86232, 2.31494},
		{"Strasbourg-Saint-Denis", 601274.000000, 2430002.000000, 48.86949, 2.35427},
		{"Denfert-Rochereau", 599760.000000, 2426181.000000, 48.833898, 2.332610},
		{"Corvisart", 600945.000000, 2425692.000000, 48.82987, 2.35066},
	}
	
	
	sl2et := "+init=IGNF:LAMBE"
	//swgs84 := "+init=espg:8326"
	sl93 := "+init=IGNF:LAMB93"



		for _, poi := range pois {
			//wgs84, _ := proj.NewProj(swgs84)
			l2et, _ := proj.NewProj(sl2et)
			l93, _ := proj.NewProj(sl93)


			//long, lat, _ := proj.Inv(l2et, poi.x, poi.y)
			x1, y1, _ := proj.Fwd(l93, poi.long, poi.lat)
			x, y, _ := proj.Transform2(l93, l2et, x1, y1)

			x2, y2, _ := proj.Transform2(l2et, l93, poi.x, poi.y)
			long, lat, _ := proj.Inv(l93, x2, y2)


			fmt.Printf("## %s : ", poi.name)
			fmt.Printf("%.0fm\n", math.Sqrt((poi.x-x)*(poi.x-x)+(poi.y-y)*(poi.y-y)))
			fmt.Printf("http://maps.google.fr?q=%f,%f\n", lat, long)
		}
}