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##### coordsys.torelmany - Function

1.1.3 Convert many numeric absolute coordinates to relative

Description

This function converts many absolute coordinates to relative. It exists so you can efficiently make many conversions (which would be rather slow if you did them all with torel). Because speed is the object, the interface is purely in terms of numeric matrices, rather than being able to accept strings and quanta etc. like torel can.

When dealing with world coordinates, the units of the numeric values must be the native units, given by function units.

Arguments

 Inputs value Absolute coordinates allowed: any Default: variant isworld Is coordinate world or pixel? Default is unset. allowed: int Default: -1
Returns
record

Example

"""
#
print "\t----\t torelmany Ex 1 \t----"
csys = cs.newcoordsys(direction=T, spectral=T)    # 3 axes
w = csys.referencevalue();                  # reference value
inc = csys.increment();                     # increment
off = []
for idx in range(100):
off.append(inc[’numeric’][2] * idx)       # offset for third axis
wabs = ia.makearray(0, [3,100])             # 100 conversions each of length 3
for i in range(3):
for j in range(100):
wabs[i][j] = w[’numeric’][i]
for j in range(100):
wabs[2][j] += off[j]                      # Make spectral axis values change
wrel  = cs.torelmany (wabs, T)[’numeric’]   # Convert
print wrel[0][0], wrel[1][0], wrel[2][0]    # First relative coordinate
#0.0 0.0 0.0
print wrel[0][99], wrel[1][99], wrel[2][99] # 100th relative coordinate
#0.0 0.0 99000.0
#
"""

This example uses world coordinates.

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