MAT-File Format - SERC
MAT-File Format - SERC MAT-File Format - SERC
1 MAT-File FormatLevel 4 MAT-File FormatNote This section is taken from the MATLAB V4.2 External InterfaceGuide, which is no longer available in printed form.This section presents the internal structure of Level 4 MAT-files. Thisinformation is provided to enable users to read and write MAT-files onmachines for which the MAT-file access routine library is not available. It is notneeded when using the MAT-file subroutine library to read and writeMAT-files, and we strongly advise that you do use the External InterfaceLibrary if it is available for all of the machines that you are working with.A MAT-file may contain one or more matrices. The matrices are writtensequentially on disk, with the bytes forming a continuous stream. Each matrixstarts with a fixed-length 20-byte header that contains information describingcertain attributes of the Matrix. The 20-byte header consists of five long(4-byte) integers:Table 1-8: Level 4 MAT-File Matrix Header FormatFieldtypeDescriptionThe type flag contains an integer whose decimal digits encode storage information. Ifthe integer is represented as MOPT where M is the thousands digit, O is the hundredsdigit, P is the tens digit, and T is the ones digit, then:M indicates the numeric format of binary numbers on the machine that wrote the file.Use this table to determine the number to use for your machine:0 IEEE Little Endian (PC, 386, 486, DEC Risc)1 IEEE Big Endian (Macintosh, SPARC, Apollo,SGI, HP 9000/300,other Motorola)2 VAX D-float3 VAX G-float4 Cray1-36
Level 4 MAT-File FormatTable 1-8: Level 4 MAT-File Matrix Header Format (Continued)O is always 0 (zero) and is reserved for future use.P indicates which format the data is stored in according to the following table:0 double-precision (64-bit) floating point numbers1 single-precision (32-bit) floating point numbers2 32-bit signed integers3 16-bit signed integers4 16-bit unsigned integers5 8-bit unsigned integersThe precision used by the save command depends on the size and type of each matrix.Matrices with any noninteger entries and matrices with 10,000 or fewer elements aresaved in floating point formats requiring 8 bytes per real element. Matrices with allinteger entries and more than 10,000 elements are saved in the following formats,requiring fewer bytes per element.Element rangeBytes per element[0:255] 1[0:65535] 2[-32767:32767] 2[-2^31+1:2^31-1] 4other 8T indicates the matrix type according to the following table:0 Numeric (Full) matrix1 Text matrix2 Sparse matrixNote that the elements of a text matrix are stored as floating point numbers between0 and 255 representing ASCII-encoded characters.1-37
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1 <strong>MAT</strong>-<strong>File</strong> <strong>Format</strong>Level 4 <strong>MAT</strong>-<strong>File</strong> <strong>Format</strong>Note This section is taken from the <strong>MAT</strong>LAB V4.2 External InterfaceGuide, which is no longer available in printed form.This section presents the internal structure of Level 4 <strong>MAT</strong>-files. Thisinformation is provided to enable users to read and write <strong>MAT</strong>-files onmachines for which the <strong>MAT</strong>-file access routine library is not available. It is notneeded when using the <strong>MAT</strong>-file subroutine library to read and write<strong>MAT</strong>-files, and we strongly advise that you do use the External InterfaceLibrary if it is available for all of the machines that you are working with.A <strong>MAT</strong>-file may contain one or more matrices. The matrices are writtensequentially on disk, with the bytes forming a continuous stream. Each matrixstarts with a fixed-length 20-byte header that contains information describingcertain attributes of the Matrix. The 20-byte header consists of five long(4-byte) integers:Table 1-8: Level 4 <strong>MAT</strong>-<strong>File</strong> Matrix Header <strong>Format</strong>FieldtypeDescriptionThe type flag contains an integer whose decimal digits encode storage information. Ifthe integer is represented as MOPT where M is the thousands digit, O is the hundredsdigit, P is the tens digit, and T is the ones digit, then:M indicates the numeric format of binary numbers on the machine that wrote the file.Use this table to determine the number to use for your machine:0 IEEE Little Endian (PC, 386, 486, DEC Risc)1 IEEE Big Endian (Macintosh, SPARC, Apollo,SGI, HP 9000/300,other Motorola)2 VAX D-float3 VAX G-float4 Cray1-36
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