Matlab fortune-telling command _matlab calculation command

MATLAB file operation related commands

Input and output statements

(1) real-time interactive input and output

Input; keyboard

(2) Full copy file access

* 1) save

rescue

Save "file name" x

Save the file name x y z

Save the file name x y z -ascii.

Save the file name x y z -ascii -double.

Save the file name x y z-ascii- double tab.

Save "existing file name" x y z attachment

Note 1: The saved default file name is fname.m

Note 2:–ASCII 8-byte ASCII code mode

Note 3:–ASCII16 byte ASCII code mode

Note 3:–ASCII–Double Tab Format Arrangement

Note 3:–Append is stored after continuation.

*2) Load

load

Load "file name"

Note that the default file name of 1:load is fname.m

(3) file access management (creation, reading and writing)

File management (open, write, read, close, locate),

*1) "fopen" opens the file and gives it a code.

Syntax 1: FID = fopen (file name, permission)

Open the file in the specified way.

FID=+N(N is a positive integer): indicates that the file was opened successfully, and the file code is n. 。

FID=- 1: indicates that the file was not opened successfully.

FID is always valid until this file is closed.

If it is opened by reading, matlab will search the working directory first, and then search other directories of matlab. Permission is an open mode parameter.

The open mode parameters are determined by the following string:

R reading

Write (if the file does not exist, it will be created automatically)

Subsequent writes (if the file does not exist, it will be created automatically)

R+ read and write (file should already exist)

W+ refresh write, (if the file does not exist, it will be created automatically)

A+ Subsequent writes (automatically created if the file does not exist))

W rewritten, but not automatically refreshed.

A Subsequent writes, but no automatic refresh.

File storage format: The default way to open files is binary. Open as text, you can use the method parameter.

For example, adding the "t" file to the number "permission" would be "rt" and "wt+".

Syntax 2: [FID, message] = fopen (file name, permission)

FID=- 1, when the file is not opened successfully, an error message is returned.

Syntax 3: [FID, message] = fopen (file name, permission, machine format)

Permission: Open the file in the specified way.

Machineformat: specifies the data format used for reading and writing.

The data format (machine format) values are as follows

"Native" or "n" local machine format-default

Ieee-le' or' l' IEEE floating-point number (little endian sorting)

"Ieee-be" or "B" IEEE floating-point number (big endian sorting)

"Vaxd" or "Vaxd floating point number (VAX order)

"Vaxg" or "Vaxg floating point number (VAX order)

"Cray" or "C" Cray floating point number (big endian sort)

Long data

Ieee-le.l64' or' a' IEEE floating-point number (little endian sorting and 64 bits)

Long data type

Iecc-be.l64' or' s' IEEE floating-point number (big byte sort and 64 bits)

Long data width

Syntax 4:[ file name, authority, machine format ]=fopen(fid).

View file opening and return file name, opening method and file format. If fid does not exist, a variable is returned.

fid=fopen('allall ')

Returns all currently open files.

* 2) "fwrite" writes data to a file in binary form.

Syntax 1: count = fwrite (fid, a, precision)

Write the matrix a into the open file pointed by fid, and matlab will automatically convert the value of a into the precision specified by Precision (see below) and write it in the form of columns. Count is the return value. If the writing is successful, the number of data written is returned, otherwise, 0 is returned.

Syntax 2: count = fwrite (FID, a, precision, skip)

Skip: take a positive integer n,

Write the matrix a into the open file pointed by fid with the jump value of step n, for example, a= 1, 2, 3, 4, 5, 6, 7, 8, 9; skip = 2； Then enter _, _, 3, _, _, 6, _, _, 9. This is significant for discontinuous data fields and fixed-length inserted data.

* 3) "FREAD" reads data from a file in binary form.

Syntax 1: [a, count] = fread (FID, size, precision)

Syntax 2: [a, count] = fread (FID, size, precision, skip)

Size: Unspecified: Returns reading from beginning to end.

N: read n data to form a column vector.

Inf: Read all the data of the open file pointed by fid.

[M, N]: read n data to form a column vector and fill in the M*N matrix.

Accuracy (Precision)

Precision specifies the number of bytes when reading floating-point numbers, integers and characters. The precision expression of matlab is consistent with C language and fortran language. If precision is not specified, the character defaults to: ucher and the value defaults to: double precision.

The following accuracy will ensure that the readings have a consistent volume.

MATLAB C or Fortran descriptor (precision)

Char' 'char*l' 8 bytes, character type

Uchar'' unsigned character' 8 bytes

Schar'' signed character'' 8 bytes, character type

Int8' 'integer* 1' 8 bytes, integer

Intl6' 'integer*2' 16 bytes, integer.

Int32' 'integer*4' 32 bytes, integer.

Int64' 'integer*8' 64 bytes, integer.

Uint8'' integer *l' 8 bytes

Uintl6' 'integer*2' 16 bytes

Uint32'' Integer *4' 32 bytes

Uint64'' Integer *8' 64 bytes

Float32' 'real*4'' floating point number, 32 bytes.

Float64' 'real*8'' floating point number, 32 bytes.

The following accuracy does not guarantee that the readings have a consistent volume.

MATLAB C or Fortran descriptor (precision)

Short' 'short' 16 bytes, integer

Int' 'int' 32 bytes, integer

Long' 'long' 32 (64) bytes, integer

Usport'' unsigned short integer' 16 bytes.

Uint'' unsigned integer'' 32 bytes

Ulong'' unsigned long integer' 32 (64) bytes

Float' 'float' floating point number, 32 bytes.

Double' 'double' floating point number, 64 bytes.

The following precision specifies reading the specified volume n.

BitN' N bytes, integer 1

Ubitrn' n bytes, 1

*4) Read the data in fscanf format from the file.

Grammar 1: [a, count] = fscanf (FID, format, size)

According to the specified format, read data from fid file in format format and store it in memory in size format.

A: variable name of data read into memory.

Count: Return value. 0: failure, n>0: success, n is the number of times to read data.

Fid: document number

Size: the format of the data.

N: column vector

Inf: Read all the data of the file.

[M, N]: put the read data into the variable name a in the format of m * n.

Format: the format of reading data.

Format is a character form, which is basically the same as C language. There are "%"in character form and character set (D, I, O, U, X, E, F, G, S, C, ...).

Such as: %s: single character reading

%c: read space characters

Example: s=fscanf(fid,' %s') returns a character.

A=fscanf(fid,' %5d') returns a five-digit decimal integer.

*5) Close the file fclose

Grammar 1: fclose (FID)

Syntax 2: fclose ('all')

*6) Write data into the file printf.

Syntax 1: count = printf (FID, format, a, b, s, ...)

Example:

x = 0:0. 1: 1；

y =[x； exp(x)]；

fid=fopen('exp.txt '，' w ')

fprintf(fid，' %6.2 % 12.8f\n '，y)；

Calculation result:

0.0 1.00000000

0. 1 1. 105 17092

1.00 2.7 1828 183

*8) Put the pointer in the file header: frewind

Grammar 1: Frewind (FID)

Hans-font-family:' New Romance of the Times'; MSO-ascii-font-family:' Times New Roman ' " & gt； The following precision specifies reading the specified volume n.

BitN' N bytes, integer 1

Ubitrn' n bytes, 1

*4) Read the data in fscanf format from the file.

Grammar 1: [a, count] = fscanf (FID, format, size)

According to the specified format, read data from fid file in format format and store it in memory in size format.

A: variable name of data read into memory.

Count: Return value. 0: failure, n>0: success, n is the number of times to read data.

Fid: document number

Size: the format of the data.

N: column vector

Inf: Read all the data of the file.

[M, N]: put the read data into the variable name a in the format of m * n.

Format: the format of reading data.

Format is a character form, which is basically the same as C language. There are "%"in character form and character set (D, I, O, U, X, E, F, G, S, C, ...).

Such as: %s: single character reading

%c: read space characters

Example: s=fscanf(fid,' %s') returns a character.

A=fscanf(fid,' %5d') returns a five-digit decimal integer.

*5) Close the file fclose

Grammar 1: fclose (FID)

Syntax 2: fclose ('all')

*6) Write data into the file printf.

Syntax 1: count = printf (FID, format, a, b, s, ...)

Example:

x = 0:0. 1: 1；

y =[x； exp(x)]；

fid=fopen('exp.txt '，' w ')

fprintf(fid，' %6.2 % 12.8f\n '，y)；

Calculation result:

0.0 1.00000000

0. 1 1. 105 17092

1.00 2.7 1828 183

*8) Put the pointer in the file header: frewind

Grammar 1: Frewind (FID)