Great circle 



A circle on the surface of the earth, 

 the plane of which passes through the 

 center of the earth. 



Header card 



The first card or cards of a deck of 

 punched cards containing identifi- 

 cation of fixed information about the 

 punched cards of variable data that 

 follow. 



Independent variable 



Input 



Interpolation 



Lock-up table 



A variable whose assigned value (s) are 

 arbitrary when defined as a function 

 of another variable, i.e., if y is 

 given as a function of x, then, x is 

 the independent variable. 



(1) The data to be processed. (2) The 

 stage or sequence of states occurring 

 on a specified input channel. (3) The 

 device or collective set of devices 

 used for bringing data into another 

 device. (4) A channel for impressing 

 a state on a device or logic element. 



(5) The process of transferring data 

 from an external storage to an 

 internal storage. 



To determine intermediate values 

 between given fixed values. As 

 applied to logical contouring to 

 interpolate is to ratio vertical 

 distances between given spot elevations. 



An index file or array (s) which is 

 usually used to access a main record 

 file. It contains the identifier (or 

 file key) and the storage address in 

 sequential or non-sequential order. 

 It may also contain critical infor- 

 mation. 



MARSDEN chart 



A system introduced by Marsden early 

 in the nineteenth century for showing 

 the distribution of meteorological 

 data on a chart; especially over the 

 oceans. A Mercator map projection is 

 used; the world between 90°N and 80°S 

 being divided into Marsden "squares" 

 each of 10° latitude by 10° longitude. 



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