Fortran常用函数

1

、

RANDOM_ NUMBER

Syntax

['sint?ks]

n.

语法

CALL RANDOM_NUMBER (

harvest< /p>

结果

)

Intrinsic Subroutine

（

固有子程序）

：

Returns a pseudorandom number greater than or equal

to zero and less than one from the uniform distribution.

返回大于或等于

0

且小于

1

，服从均匀分布的随机数

2

、

RNNOA/ DRNNOA

（

Single/Double precision

）

Generate pseudorandom numbers from a standard normal distribution using an

acceptance/rejection method.

产生服从标准正态分布的随机数

Usage

（用法）

CALL RNNOA (NR, R)

Arguments

（参数）

NR

—

Number of random numbers to generate.

(Input)

要产生随机数的个数

R

—

Vector of length

NR

containing the random standard normal deviates.

(Output)

输出长度为

NR

，随机正态分布的向量

Comments

（注解）

The routine RNSET can be used to initialize the seed of the random number generator.

The routine RNOPT can be used to select the form of the generator.

< br>程序

RNSET

可以用来初始化随机数发生器的种子

Example

In this example,

RNNOA

is used to generate five pseudorandom deviates from a standard

normal distribution.

INTEGER ISEED, NOUT, NR

REAL R(5)

EXTERNAL RNNOA, RNSET, UMACH

C

CALL UMACH (2, NOUT)

NR = 5

ISEED = 123457

CALL RNSET (ISEED)

CALL RNNOA (NR, R)

WRITE (NOUT,99999) R

99999 FORMAT (' Standard normal random deviates: ', 5F8.4)

END

Output

Standard normal random deviates: 2.0516 1.0833 0.0826 1.2777

-1.2260

3

、

RESHAPE

Intrinsic Function

（内部函数）

Constructs an array of a specified shape from the elements

of another array.

构造规定形式的数组

Syntax

（语法）

result

=

RESHAPE

(

source

,

shape

[ ,

pad

]

[ ,

order

]

)

source

(Input)

Any type. Array whose elements will be taken in standard Fortran array order

(see Remarks), and then placed into a new array.

shape

(Input)

Integer. One-dimensional array that describes the shape of the output array

created from elements of

source

.

描述输出数组的大小的一维数组，

The elements of

shape

are the sizes of the dimensions of the reshaped array in order. If

pad

is omitted

省略

, the total size specified by

shape

must be less than or equal to

source.

pad

可选参数

(Optional; input)

Same type as

source

. Must be an array. If there are not enough

elements in

source

to fill the result array, elements of

pad

are added in standard

Fortran array order. If necessary, extra copies of

pad

are used to fill the array.

order

可选参数

(Optional; input)

Integer. One- dimensional array. Must be the same length as

shape

.

Permutes the order of dimensions in the result array. The value of

order

must be a

permutation of (

1, 2,...n

) where

n

is the size of

shape

.

Return Value

（返回值）

The result is an array the same data type and kind as

source

and a shape as defined in

shape

.

Examples

INTEGER AR1( 2, 5)

REAL F(5,3,8)

REAL C(8,3,5)

AR1 = RESHAPE((/1,2,3,4,5,6/),(/2,5/),(/0,0/),(/2,1/))

! returns 1 2 3 4 5

! 6 0 0 0 0

!

! Change Fortran array order to C array order

C = RESHAPE(F, (/8,3,5/), ORDER = (/3, 2, 1/))

END

4

、

SUM

Intrinsic Function

（内部函数）

Sums elements of an array or the elements along an

optional dimension. The elements summed can be selected by an optional mask.

将数组中的元素求和

Syntax

（语法）

result

=

SUM

(

array

[ ,

dim

] [ ,

mask

]

)

array

(Input)

Integer, real, or complex. Array whose elements are to be summed.

dim

可选参数

(Optional; input)

Integer. Dimension along which elements are summed.

1

?

dim

?

n

, where

n

is the number of dimensions in

array

.

mask

可选参数

(Optional; input)

Logical. Must be same shape as

array

. If

mask

is specified, only

elements in

array

that correspond to

.TRUE.

elements in

mask

are summed.

Return Value

（返回值）

Same type and kind as

array

and equal to the sum of all elements in

array

or the sum of

elements along dimension

dim

. If

mask

is specified, only elements that correspond

to

.TRUE.

elements in

mask

are summed. Returns a scalar if

dim

is omitted or

array

is

one- dimensional. Otherwise, returns an array one dimension smaller than

array

.

Examples

INTEGER array (2, 3), i, j(3)

array = RESHAPE((/1, 2, 3, 4, 5, 6/), (/2, 3/))

! array is 1 3 5

! 2 4 6

i = SUM((/ 1, 2, 3 /)) ! returns 6

j = SUM(array, DIM = 1) ! returns [3 7 11]

WRITE(*,*) i, j

END

5

、

SEED

Run-Time Subroutine

Changes the starting point of the pseudorandom number

generator.

改变随机数发生器的起始点

Module

USE

MSFLIB

Syntax

（语法）

CALL

SEED

(

iseed

)

iseed

(Input)

INTEGER(4). Starting point for

RANDOM

.

Remarks

（注解）

SEED

uses

iseed

to establish the starting point of the pseudorandom number generator.

A given seed always produces the same sequence of values from

RANDOM

.

If

SEED

is not called before the first call to

RANDOM

,

RANDOM

always begins with a

seed value of one. If a program must have a different pseudorandom sequence each time

it runs, pass the constant

RND$$TIMESEED

(defined in MSFLIB.F90) to the

SEED

routine

before the first call to

RANDOM

.

Example

USE MSFLIB

REAL rand

CALL SEED(7531)

CALL RANDOM(rand)

6

、< /p>

RANDOM

Purpose

Run-Time Subroutine

Returns a pseudorandom number greater than or equal to

zero and less than one from the uniform distribution.

返回大于或等于< /p>

0

且小于

1

，服 从均匀

分布的随机数

Module

USE

MSFLIB

Syntax

CALL

RANDOM

(

ranval

)

ranval

(Output)

REAL(4). Pseudorandom number, 0

?

ranval

?

1, from the uniform

distribution.

Remarks

A given seed always produces the same sequence of values from

RANDOM

.

If

SEED

is not called before the first call to

RANDOM

,

RANDOM

begins with a seed value

of one. If a program must have a different pseudorandom sequence each time it runs,

pass the constant

RND$$TIMESEED

(defined in MSFLIB.F90) to

SEED

before the first call

to

RANDOM

.

All the random procedures (

RANDOM

,

RAN

,

and

RANDOM_NUMBER

, and the PortLib

functions

DRAND

,

DRANDM

,

RAND

,

IRANDM

,

RAND

, and

RANDOM)

use the same

algorithms and thus return the same answers. They are all compatible and can be used

interchangeably. (The algorithm used is a “Prime Modulus M Multiplicative Linear

Congruential Generator,” a modified version of t

he random number generator by Park and

Miller in “Random Number Generators: Good Ones Are Hard to Find,” CACM, October

1988, Vol. 31, No. 10.)

Compatibility

CONSOLE

STANDARD GRAPHICS

QUICKWIN GRAPHICS

WINDOWS

DLL

LIB

Example

USE MSFLIB

REAL(4) ran

CALL SEED(1995)

CALL RANDOM(ran)

7

、

FFT2B

Compute the inverse Fourier transform of a complex periodic two-dimensional array.

计算二维复数数组的逆傅里叶变换

Usage

（用法）