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The coordinate conversion commands include:
Xuser,
Yuser,
User,
Pts,
Inches,
Mm,
Cm,
NDC, and
Loran.
All of the following functions (except NDC) accept values in one unit of measure and return the value converted
to Normalized Device Units. Normalized Device Units normally range
in value from 0.0 to 1.0.
The lower left corner of the output "page"
is (0,0) and the upper right corner of a 8.5 x
11 inch page is usually (0.772727,1.0) NDCs.
1.0 NDC = 11 inches = 792 pts = 279.4 mm = 27.94
cm
This function converts a numeric value in x axis
coordinate units to Normalized Device Units. This function returns
a numeric value.
- There is 1 parameter:
- value - an integer or floating point numeric value (or vector
or matrix).
xuser(value);
xuser(-67.5);
0.204804
See the example Filled Arrows
affected by Data_Window(), Data_Viewport(), Data_Projection().
This function converts a numeric value in y axis
coordinate units to Normalized Device Units. This function returns
a numeric value.
- There is 1 parameter:
- value - an integer or floating point numeric value (or vectoror matrix).
yuser(value);
yuser(42.5);
0.311382
See the example Filled Arrows
affected
by Data_Window(), Data_Viewport(), Data_Projection().
This function converts numeric values in user units
to Normalized Device Coordinates.
- There 1 or 2 parameters:
- x, y values - integer or floating point numeric value or vectors in user units.
- or
- matrix - integer or floating point matrix (n x 2) in user units.
User(x,y value);
User(-69.5272 40.2285);
0.1 0.1
affected by Data_Window(), Data_Viewport(), Data_Projection().
This function converts numeric values in user units
to Normalized Device Coordinates. This function is identical to
the User() function except that if an
extended projection is active, additional interpolated values are
returned in addition to the original data points.
Note that the actual values returned would be unique for any given projection.
- There 1 or 2 parameters:
- x, y values - integer or floating point numeric value or vectors
in user units.
- or
- matrix - integer or floating point matrix (n x 2) in user units.
User_Proj(x,y value);
x = -60 -66;
y = 44 48;
// using a simple projection, no intermediate points are returned
Data_projection("MERCATOR");
xyNDCs = user_proj(x,y); // convert to NDC units
Line_Colour("GREEN");
Draw(xyNDCs);
Line_Colour("BLACK");
Axis(1.,1.,0.,0.,1,0,1,0,0);
// using an extended projection, intermediate points are returned
p2 = "proj=MERC lon_0=59.0w lat_ts=44n ellps=clrk66 R_A"; // Mercator
Data_projection(p2);
xyNDCs = user_proj(x,y); // convert to NDC units
Line_Colour("RED");
Draw(xyNDCs);
Line_Colour("BLUE");
xyUser = NDC(xyNDCs); // convert back to lon, lat values
Data_Line(xyUser);
Line_Colour("BLACK");
Axis(1.,1.,0.,0.,1,0,1,0,0);
affected by Data_Window(), Data_Viewport(), Data_Projection().
This function converts a numeric value in PostScript
Printers points (1/72") coordinate units to Normalized Device
Units. This function returns a numeric value.
- There is 1 parameter:
- value - an integer or floating point numeric value (or vector or matrix).
pts(value);
size = pts(12);
size
0.0151515
See the example Data Points and Labels
This function converts a numeric value in inches
to Normalized Device Units. This function returns a numeric value.
- There is 1 parameter:
- value - an integer or floating point numeric value (or vector or matrix).
inches(value);
size = inches(1);
size
0.0909091
This function converts a numeric value in mm to Normalized
Device Units. This function returns a numeric value.
- There is 1 parameter:
- value - an integer or floating point numeric value (or vector or matrix).
mm(value);
mm(15.5);
0.055476
See the example Data Points and Labels
This function converts a numeric value in cm to Normalized
Device Units. This function returns a numeric value.
- There is 1 parameter:
- value - an integer or floating point numeric value (or vector or matrix).
cm(value);
cm(2.5);
0.0894775
This function converts a numeric value in Normalized
Device Coordinates to user units.
- There are 1 or 2 parameters:
- x, y values - integer or floating point numeric value or vectors(NDC range is from 0 - 1).
- or
- matrix - integer or floating point matrix (n x 2).
NDC(x,y value);
ndc(0.1,0.1);
-69.5272 40.2285
This function converts loran C readings to longitude latitude. The original source of the code used in
this conversion is unsure, so please confirm your results independently.
- There are 6+ parameters:
- x reading - floating point numeric value or vector.
- x chain - character string or character matrix.
- y reading - floating point numeric value or vector.
- y chain - character string or character matrix.
- x start - floating point numeric value or vector giving a starting estimate for the returned longitude.
- y start - floating point numeric value or vector giving a starting estimate for the returned longitude.
- method - optional flag indicating the type of loran conversion to use (0 = default, 1 = method used by original lobster data conversion code).
xymatrix = Loran(read1,chain1,read2,chain2,startx,starty,[method]);
Loran(13873.5,"593X",31205.6,"593Y",-65.5,44.9,0)
-65.913163 44.686340
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