doc: example

v5/doc.go

@@ -7,5 +7,27 @@ This package supports PROJ version 5 and above.
 
 For PROJ.4, see: https://github.com/pebbe/go-proj-4
 
+Example usage:
+
+    ctx := proj.NewContext()
+    defer ctx.Close() // if omitted, this will be called on garbage collection
+
+    pj, err := ctx.Create(`
+        +proj=pipeline
+        +step +proj=unitconvert +xy_in=deg +xy_out=rad
+        +step +proj=utm +zone=31
+    `)
+    if err != nil {
+        log.Fatal(err)
+    }
+    defer pj.Close() // if omitted, this will be called on garbage collection
+
+    x, y, _, _, err := pj.Trans(proj.Fwd, 3, 58, 0, 0)
+    if err != nil {
+        log.Fatal(err)
+    }
+
+    fmt.Println(x, y)
+
 */
 package proj

v5/proj.go

@@ -182,7 +182,7 @@ Transform a series of coordinates, where the individual coordinate dimension may
 
 3. of length one, i.e. a constant, which will be treated as a fully populated slice of that constant value
 
-TODO: what if input is constant, but output is not?
+Note: if an input coordinate is constant, but the output coordinate varies, you need to supply a fully populated slice as input
 */
 func (p *PJ) TransSlice(direction Direction, u1, v1, w1, t1 []float64) (u2, v2, w2, t2 []float64, err error) {
 	if !p.opened {

v5/utm.go

@@ -12,7 +12,7 @@ import (
 func UTMzone(lng, lat float64) (xzone int, yzone string, err error) {
 
 	if lat < -80 || lat > 84 {
-		err = errors.New("Arctic and antarctic region are not in UTM")
+		err = errors.New("Arctic and Antarctic region are not in UTM")
 		return
 	}
 
@@ -23,7 +23,7 @@ func UTMzone(lng, lat float64) (xzone int, yzone string, err error) {
 		lng -= 360
 	}
 
-	xzone = 1 + int((lng + 180) / 6)
+	xzone = 1 + int((lng+180)/6)
 	if lat > 72 && lng > 0 && lng < 42 {
 		if lng < 9 {
 			xzone = 31
@@ -39,7 +39,7 @@ func UTMzone(lng, lat float64) (xzone int, yzone string, err error) {
 		xzone = 32
 	}
 
-	yzone = string("CDEFGHJKLMNPQRSTUVWXX"[int((lat + 80) / 8)])
+	yzone = string("CDEFGHJKLMNPQRSTUVWXX"[int((lat+80)/8)])
 
-    return
+	return
 }