# TRIPLE INTERPOLATION

 Interpolation when there are three arguments or variables.

## Related Terms

### INTERPOLATION

The process of determining intermediate values between given values in accordance with some known or assumed rate or system of change. Linear interpolation assumes that changes of tabulated values are proportional to changes in entering argu- ments. Interpolation is designated as single, double, or triple if there are one, two, or three arguments or variables respectively.

### LINEAR INTERPOLATION

Interpolation in which changes of tabulated values are assumed to be proportional to changes in entering arguments.

### COMPUTED ALTITUDE

1. Tabulated altitude interpolated for increments of latitude, declination, or hour angle. If no interpolation is required, the tabulated altitude and computed altitude are identical. 2. Altitude determined by computation, table, mechanical computer, or graphics, particularly such an altitude of the center of a celestial body measured as an arc on a vertical circle of the celestial sphere from the celestial horizon. Also called CALCULATED ALTITUDE.

### CRITICAL TABLE

A single entering argument table in which values of the quantity to be found are tabulated for limiting values of the entering argument. In such a table interpolation is avoided through dividing the argument into intervals so chosen that successive intervals correspond to successive values of the required quantity, called the respondent. For any value of the argument within these intervals, the respondent can be extracted from the table without interpolation. The lower and upper limits (critical values) of the argument correspond to half-way values of the respondent and, by convention, are chosen so that when the argument is equal to one of the critical values, the respondent corresponding to the preceding (upper) interval is to be used.

### SINGLE INTERPOLATION

Interpolation with only one argument or variable.

### TABULATED ALTITUDE

In navigational sight reduction tables, the altitude taken directly from a table for the entering arguments. After interpolation for argument increments, i.e., the difference between each entering argument and the actual value, it is called COMPUTED ALTITUDE. Also called TABULAR ALTITUDE.

### Related questions

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