# Template:Location map Tuvalu

name border map center coordinates Tuvalu -5.3 175.7 ←↕→ -179.8 -11.0 8°09′S 177°57′E﻿ / ﻿8.15°S 177.95°E (100*(({{{3}}} + ({{{3}}} < 0)*360) - 175.7)/((-179.8 + 360) - 175.7)) (100*({{{2}}} - (-5.3))/((-11.0) - (-5.3))) Tuvalu location map.svg
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Template:Location map Tuvalu is a location map definition used to overlay markers and labels on an equirectangular projection map of Tuvalu. The markers are placed by latitude and longitude coordinates on the default map or a similar map image.

## Usage

These definitions are used by the following templates when invoked with parameter "Tuvalu":

• `{{Location map | Tuvalu | ...}}`
• `{{Location map many | Tuvalu | ...}}`
• `{{Location map+ | Tuvalu | ...}}`
• `{{Location map~ | Tuvalu | ...}}`

## Map definition

name
used in default map caption (Tuvalu)
image
the default map image, without "Image:" or "File:" (Tuvalu location map.svg)
x
an expression to calculate a location on the map via its longitude; evaluates as 0 along the left edge and 100 along the right edge
y
an expression to calculate a location on the map via its latitude; evaluates as 0 along the top edge and 100 along the bottom edge

### Technical details

For a map using an equirectangular projection which does not cross +/-180 longitude, or +/-90 latitude, the following expressions can be used:

`x = 100*(long - left)/(right - left)`
`y = 100*(lat - top)/(bottom - top)`

where lat and long are the degrees latitude and longitude respectively. Here, top and bottom are the degrees latitude of the top and bottom edges of the map, left and right are the degrees latitude of the left and right edges of the map.

Things are a bit more complicated when the map crosses +/-180 longitude, and some sort of "modulo arithmetic" is required. Here, we add 360 if the longitude is less than 0, then use a mapping based on positive coordinates. The following table can be used to check if the expressions are working as desired:

location lat long (x,y) test (x,y) exact
top/left -5.3 175.7 (0,0) (0,0)
top/right -5.3 -179.8 (100,0) (100,0)
bottom/left -11.0 175.7 (0,100) (0,100)
bottom/right -11.0 -179.8 (100,100) (100,100)
center -8.15 177.95 (50,50) (50,50)

## Examples

### Location map: Eastern hemisphere, Deg/Min/Sec coordinates

Nanumea
Nanumea in Tuvalu
```{{Location map | Tuvalu
| width = 150
| caption = [[Nanumea]] in Tuvalu
| label = Nanumea
| lat_deg= 05 | lat_min=41 | lat_sec= | lat_dir=S
| lon_deg=176 | lon_min=12 | lon_sec= | lon_dir=E
| background = lightblue
| position = right
}}
```

### Location map: Eastern hemisphere, Decimal coordinates

Nanumea
Nanumea in Tuvalu
```{{Location map | Tuvalu
| width = 150
| caption = [[Nanumea]] in Tuvalu
| lat = -5.683
| long = 176.2
| label = Nanumea
| background = lightblue
| position = right
}}
```

### Location map: Western hemisphere, Deg/Min/Sec coordinates

10°15′S 179°59′W
Coordinates on Tuvalu map
```{{Location map | Tuvalu
| width = 150
| caption = Coordinates on Tuvalu map
| lat_deg= 10 | lat_min=15 | lat_sec= | lat_dir=S
| lon_deg=179 | lon_min=59 | lon_sec= | lon_dir=W
| label = 10°15′S 179°59′W
| background = lightgreen
| position = left
}}
```

### Location map: Western hemisphere, Decimal coordinates

-10.25, -179.983333
Coordinates on Tuvalu map
```{{Location map | Tuvalu
| width = 150
| caption = Coordinates on Tuvalu map
| lat = -10.25
| long = -179.983333
| label = -10.25, -179.983333
| background = lightgreen
| position = left
}}
```