Fix floating point rounding errors

Using single precision floating point types (float32) for elements
such as latitude and longitude exposed unexpected rounding errors
in the resulting output.

Switches all floating point types to double precision (float64).

cmd/csv.go

@@ -132,7 +132,7 @@ func formatTimeCSV(date v1000.Date) string {
   return fmt.Sprintf("%02d%02d%02d", date.Hour, date.Minute, date.Second)
 }
 
-func formatLatLon(latLon float32, northSouth bool) string {
+func formatLatLon(latLon float64, northSouth bool) string {
   x := true
   var dir string
   if latLon < 0 {

cmd/gpx.go

@@ -125,9 +125,9 @@ type gpxHeader struct {
 }
 
 // latLong ...
-type latLong float32
+type latLong float64
 // other ...
-type other float32
+type other float64
 
 // MarshalXMLAttr ...
 func (value latLong) MarshalXMLAttr(name xml.Name) (xml.Attr, error) {

v1000/record.go

@@ -28,14 +28,14 @@ type Record struct {
   Index uint32
   Type string
   Time Date
-  Longitude float32
+  Longitude float64
   South bool
-  Latitude float32
+  Latitude float64
   West bool
   Altitude uint32
-  Speed float32
+  Speed float64
   Heading uint16
-  Pressure float32
+  Pressure float64
   Temperature uint16
 }
 
@@ -160,15 +160,15 @@ func parseCoords(file *os.File, rec *Record) (error) {
   if err != nil {
     return err
   }
-  rec.Latitude = float32(value) / 1000000.0
+  rec.Latitude = float64(value) / 1000000.0
   if rec.South {
     rec.Latitude = -rec.Latitude
   }
   value, err = parseLong(file)
   if err != nil {
     return err
   }
-  rec.Longitude = float32(value) / 1000000.0
+  rec.Longitude = float64(value) / 1000000.0
   if rec.West {
     rec.Longitude = -rec.Longitude
   }
@@ -189,7 +189,7 @@ func parseSpeed(file *os.File, rec *Record) error {
   if err != nil {
     return err
   }
-  rec.Speed = float32(value / 10)
+  rec.Speed = float64(value) / 10.0
   return nil
 }
 
@@ -207,7 +207,7 @@ func parsePressure(file *os.File, rec *Record) error {
   if err != nil {
     return err
   }
-  rec.Pressure = float32(value / 10)
+  rec.Pressure = float64(value) / 10.0
   return nil
 }