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man pages->IRIX man pages -> f90/alog (3)
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### Contents

```
LOG(3F)								       LOG(3F)

```

### NAME[Toc][Back]

```     log, alog,	dlog, qlog, clog, zlog - FORTRAN natural logarithm intrinsic
function
```

### SYNOPSIS[Toc][Back]

```     real r1, r2
double precision dp1, dp2
real*16 qp1, qp2
complex cx1, cx2
complex*16	cd1, cd2

r2	= alog(r1)
r2	= log(r1)

dp2 = dlog(dp1)
dp2 = log(dp1)

qp2 = qlog(qp1)
qp2 = log(qp1)

cx2 = clog(cx1)
cx2 = log(cx1)

cd2 = zlog(cd1)
cd2 = log(cd1)
```

### DESCRIPTION[Toc][Back]

```     alog returns the real natural logarithm of	its real argument.  dlog
returns the double-precision natural logarithm of its double-precision
argument.	qlog returns the real*16 natural logarithm of its real*16
argument.	The argument of	alog, dlog, and	qlog must be greater than
zero.  clog returns the complex logarithm of its complex argument.	 The
argument of clog must not be (0.,0.).  The	range of the imaginary part of
clog is: -pi < imaginary part <= pi.  zlog	returns	the complex*16
logarithm of its complex*16 argument.  The	generic	function log becomes a
call to alog, dlog, qlog, clog, or	zlog depending on the type of its
argument.
```

```     exp(3M).

Page 1

ALOG(3M)					       Last changed: 1-6-98

```

### NAME[Toc][Back]

```     ALOG, DLOG, CLOG, CDLOG - Computes	natural	logarithm
```

### SYNOPSIS[Toc][Back]

```     UNICOS and	UNICOS/mk systems:

ALOG ([X=]x)
DLOG ([X=]x)
CLOG ([X=]x)

UNICOS and	IRIX systems:
CDLOG ([X=]x)
```

### IMPLEMENTATION[Toc][Back]

```     UNICOS, UNICOS/mk,	and IRIX systems
```

### STANDARDS[Toc][Back]

```     Fortran 90
CDLOG is a	compiler extension to Fortran 90.
```

### DESCRIPTION[Toc][Back]

```     LOG is the	generic	function name.	ALOG, DLOG, and	CLOG are intrinsic
and elemental functions for CF90.

A vector version of this intrinsic	exists on UNICOS and UNICOS/mk
systems.  On UNICOS/mk systems, the vector	version	of this	intrinsic
is	used when -h vector3 (C	compiler) or -O	vector3	or -O3 (Fortran
compiler) has been	specified on the compiler command line.

The entry point CDLOG is provided for support in other languages.	It
is	not recognized as an intrinsic function; therefore, you	must use
the CDIR\$ VFUNCTION directive to allow vectorization.

These functions evaluate y	= ln(x).

CF90    [Toc]    [Back]
CDLOG is called implicitly	by the Fortran 90 compiler as a	result of a
generic ALOG call with a complex double-precision argument.

CAL Register	Usage (Cray Research Systems Only)
Scalar ALOG:  ALOG% (call-by-register)
on entry   (S1) = argument
on exit    (S1) = result

Vector ALOG:  %ALOG% (call-by-register)
on entry   (V1) = argument vector
on exit    (V1) = result vector

Scalar DLOG:  DLOG% (call-by-register)
on entry   (S1) and (S2) = argument
on exit    (S1) and (S2) = result

Vector DLOG:  %DLOG% (call-by-register)
on entry   (V1) and (V2) = argument vector
on exit    (V1) and (V2) = result vector

Scalar CLOG:  CLOG% (call-by-register)
on entry   (S1) and (S2) = argument
on exit    (S1) and (S2) = result

Vector CLOG:  %CLOG% (call-by-register)
on entry   (V1) and (V2) = argument vector
on exit    (V1) and (V2) = result vector

Scalar CDLOG:  CDLOG% (call-by-register)
on entry   (S1), (S2), (S3), (S4) = argument
on exit    (S1), (S2), (S3), (S4) = result

Vector CDLOG:  %CDLOG% (call-by-register)
on entry   (V1), (V2), (V3), (V4) = argument vector
on exit    (V1), (V2), (V3), (V4) = result vector

Argument Range		 2450
infinity is approximately 10
308
On	UNICOS/mk systems, infinity is approximately 10

ALOG, DLOG:  0 < x	< infinity

CLOG:  x must not be (0,0).

CDLOG (all	systems	except UNICOS/mk systems):  x must not be (0,0).
```

### NOTES[Toc][Back]

```     CDLOG is an outmoded routine for CF90.  Refer to the Fortran Language
Reference Manual, Volume 3, publication SR-3905, for information about
outmoded features and their preferred standard alternatives.

The name of the ALOG, DLOG, and CLOG intrinsic can	be passed as an
argument.	The name of the	CDLOG intrinsic	cannot be passed as an
argument.
```

### RETURN VALUES[Toc][Back]

```     ALOG returns the real natural logarithm of	its real argument.

DLOG returns the double-precision natural logarithm of its
double-precision argument.

CLOG returns the complex natural logarithm	of its complex argument.

CDLOG returns the complex double-precision	natural	logorithm of its
complex double-precision argument.

On	CRAY T90 systems that support IEEE arithmetic, the following return
values occur:

ALOG(0) = - infinity

ALOG(-0) = NaN

ALOG(x) = NaN	if - infinity <= x < 0

ALOG(	infinity ) = infinity
```

```     Intrinsic Procedures Reference Manual, publication	SR-2138, for the
printed version of	this man page.

ALOG(3M)					       Last changed: 1-6-98

```

### NAME[Toc][Back]

```     ALOG, DLOG, CLOG, CDLOG - Computes	natural	logarithm
```

### SYNOPSIS[Toc][Back]

```     UNICOS and	UNICOS/mk systems:

ALOG ([X=]x)
DLOG ([X=]x)
CLOG ([X=]x)

UNICOS and	IRIX systems:
CDLOG ([X=]x)
```

### IMPLEMENTATION[Toc][Back]

```     UNICOS, UNICOS/mk,	and IRIX systems
```

### STANDARDS[Toc][Back]

```     Fortran 90
CDLOG is a	compiler extension to Fortran 90.
```

### DESCRIPTION[Toc][Back]

```     LOG is the	generic	function name.	ALOG, DLOG, and	CLOG are intrinsic
and elemental functions for CF90.

A vector version of this intrinsic	exists on UNICOS and UNICOS/mk
systems.  On UNICOS/mk systems, the vector	version	of this	intrinsic
is	used when -h vector3 (C	compiler) or -O	vector3	or -O3 (Fortran
compiler) has been	specified on the compiler command line.

The entry point CDLOG is provided for support in other languages.	It
is	not recognized as an intrinsic function; therefore, you	must use
the CDIR\$ VFUNCTION directive to allow vectorization.

These functions evaluate y	= ln(x).

CF90    [Toc]    [Back]
CDLOG is called implicitly	by the Fortran 90 compiler as a	result of a
generic ALOG call with a complex double-precision argument.

CAL Register	Usage (Cray Research Systems Only)
Scalar ALOG:  ALOG% (call-by-register)
on entry   (S1) = argument
on exit    (S1) = result

Vector ALOG:  %ALOG% (call-by-register)
on entry   (V1) = argument vector
on exit    (V1) = result vector

Scalar DLOG:  DLOG% (call-by-register)
on entry   (S1) and (S2) = argument
on exit    (S1) and (S2) = result

Vector DLOG:  %DLOG% (call-by-register)
on entry   (V1) and (V2) = argument vector
on exit    (V1) and (V2) = result vector

Scalar CLOG:  CLOG% (call-by-register)
on entry   (S1) and (S2) = argument
on exit    (S1) and (S2) = result

Vector CLOG:  %CLOG% (call-by-register)
on entry   (V1) and (V2) = argument vector
on exit    (V1) and (V2) = result vector

Scalar CDLOG:  CDLOG% (call-by-register)
on entry   (S1), (S2), (S3), (S4) = argument
on exit    (S1), (S2), (S3), (S4) = result

Vector CDLOG:  %CDLOG% (call-by-register)
on entry   (V1), (V2), (V3), (V4) = argument vector
on exit    (V1), (V2), (V3), (V4) = result vector

Argument Range		 2450
infinity is approximately 10
308
On	UNICOS/mk systems, infinity is approximately 10

ALOG, DLOG:  0 < x	< infinity

CLOG:  x must not be (0,0).

CDLOG (all	systems	except UNICOS/mk systems):  x must not be (0,0).
```

### NOTES[Toc][Back]

```     CDLOG is an outmoded routine for CF90.  Refer to the Fortran Language
Reference Manual, Volume 3, publication SR-3905, for information about
outmoded features and their preferred standard alternatives.

The name of the ALOG, DLOG, and CLOG intrinsic can	be passed as an
argument.	The name of the	CDLOG intrinsic	cannot be passed as an
argument.
```

### RETURN VALUES[Toc][Back]

```     ALOG returns the real natural logarithm of	its real argument.

DLOG returns the double-precision natural logarithm of its
double-precision argument.

CLOG returns the complex natural logarithm	of its complex argument.

CDLOG returns the complex double-precision	natural	logorithm of its
complex double-precision argument.

On	CRAY T90 systems that support IEEE arithmetic, the following return
values occur:

ALOG(0) = - infinity

ALOG(-0) = NaN

ALOG(x) = NaN	if - infinity <= x < 0

ALOG(	infinity ) = infinity
```

```     Intrinsic Procedures Reference Manual, publication	SR-2138, for the