REAL FUNCTION GAINTERB ( GAINAB, FREQOPER )
Argument Definitions (+ indicates altered content)
REAL               FREQOPER,   GAINAB(*)
Description
interpolate directivity gain given: 
    gainab(2-30) = gain @  2 - 30 MHz 
    freqoper      = operating frequency
Source file:gainterb.f
Intrinsic Functions Called
REAL               FLOAT
Local Variables (+ indicates altered content)
INTEGER           +IDX
REAL              +FACT