Appendix A. Intrinsic & basic external function reference

This is the standard's function library: the intrinsic functions of Table 3 (§8.2) and the basic external functions of Table 4 (§8.3.3). FORTRAN 66 has no generic dispatch — you choose the spelling that matches your data's type (ABS for real, IABS for integer, DABS for double precision). All of these are verified present in forterp.

Table 3 — intrinsic functions

Function	Definition	Args	Name	Arg type	Result type
Absolute value	|a|	1	ABS	real	real
		1	IABS	integer	integer
		1	DABS	double	double
Truncation	sign of a × largest integer ≤ |a|	1	AINT	real	real
		1	INT	real	integer
		1	IDINT	double	integer
Remaindering	a₁ (mod a₂)	2	AMOD	real	real
		2	MOD	integer	integer
Largest value	max(a₁, a₂, …)	≥2	AMAX0	integer	real
		≥2	AMAX1	real	real
		≥2	MAX0	integer	integer
		≥2	MAX1	real	integer
		≥2	DMAX1	double	double
Smallest value	min(a₁, a₂, …)	≥2	AMIN0	integer	real
		≥2	AMIN1	real	real
		≥2	MIN0	integer	integer
		≥2	MIN1	real	integer
		≥2	DMIN1	double	double
Float	integer → real	1	FLOAT	integer	real
Fix	real → integer	1	IFIX	real	integer
Transfer of sign	sign of a₂ × |a₁|	2	SIGN	real	real
		2	ISIGN	integer	integer
		2	DSIGN	double	double
Positive difference	a₁ − min(a₁, a₂)	2	DIM	real	real
		2	IDIM	integer	integer
Most significant part of double		1	SNGL	double	real
Real part of complex		1	REAL	complex	real
Imaginary part of complex		1	AIMAG	complex	real
Single → double		1	DBLE	real	double
Two reals → complex	a₁ + a₂√−1	2	CMPLX	real	complex
Conjugate of complex		1	CONJG	complex	complex

AMOD, MOD, SIGN, ISIGN, and DSIGN are not defined when the second argument is zero (§8.2).

Table 4 — basic external functions

Function	Definition	Args	Name	Arg type	Result type
Exponential	eᵃ	1	EXP	real	real
		1	DEXP	double	double
		1	CEXP	complex	complex
Natural logarithm	logₑ(a)	1	ALOG	real	real
		1	DLOG	double	double
		1	CLOG	complex	complex
Common logarithm	log₁₀(a)	1	ALOG10	real	real
		1	DLOG10	double	double
Sine	sin(a)	1	SIN	real	real
		1	DSIN	double	double
		1	CSIN	complex	complex
Cosine	cos(a)	1	COS	real	real
		1	DCOS	double	double
		1	CCOS	complex	complex
Hyperbolic tangent	tanh(a)	1	TANH	real	real
Square root	a^(1/2)	1	SQRT	real	real
		1	DSQRT	double	double
		1	CSQRT	complex	complex
Arctangent	arctan(a)	1	ATAN	real	real
		1	DATAN	double	double
	arctan(a₁/a₂)	2	ATAN2	real	real
		2	DATAN2	double	double
Remaindering	a₁ (mod a₂)	2	DMOD	double	double
Modulus	|a|	1	CABS	complex	real

      COMMON /O/ R(3)
      REAL R
      R(1) = SQRT(2.0)
C     -> 1.41421
      R(2) = ATAN2(1.0, 1.0)
C     -> 0.78540  (pi/4)
      R(3) = ABS(SIGN(5.0, -1.0))
C     -> 5.0  (magnitude of 5, sign of -1, then absolute value)

forterp notes. forterp implements the complete Table 3 and Table 4 libraries on every dialect. It also offers many DEC FORTRAN-10 intrinsics beyond the standard set (extra type variants and service routines); those are listed with the other extensions in Appendix C. Stay within the tables above for portable code. On the default NATIVE target the results carry host (64-bit) precision; the PDP10 target reproduces the DEC-10 library's precision and edge-case behavior.