Interface to MATLAB

According to their website, MATLAB is “a high-level language and interactive environment that enables you to perform computationally intensive tasks faster than with traditional programming languages such as C, C++, and Fortran.”

The commands in this section only work if you have the “matlab” interpreter installed and available in your PATH. It’s not necessary to install any special Sage packages.

EXAMPLES:

sage: matlab.eval('2+2')                 # optional - matlab
'\nans =\n\n     4\n'
sage: a = matlab(10)                     # optional - matlab
sage: a**10                              # optional - matlab
   1.0000e+10

AUTHORS:

  • William Stein (2006-10-11)

Tutorial

EXAMPLES:

sage: matlab('4+10')                    # optional - matlab
14
sage: matlab('date')                    # optional - matlab; random output
18-Oct-2006
sage: matlab('5*10 + 6')                # optional - matlab
56
sage: matlab('(6+6)/3')                 # optional - matlab
4
sage: matlab('9')^2                     # optional - matlab
81
sage: a = matlab(10); b = matlab(20); c = matlab(30)    # optional - matlab
sage: avg = (a+b+c)/3 ; avg             # optional - matlab
20
sage: parent(avg)                       # optional - matlab
Matlab
sage: my_scalar = matlab('3.1415')       # optional - matlab
sage: my_scalar                          # optional - matlab
3.1415
sage: my_vector1 = matlab('[1,5,7]')     # optional - matlab
sage: my_vector1                         # optional - matlab
1     5     7
sage: my_vector2 = matlab('[1;5;7]')     # optional - matlab
sage: my_vector2                         # optional - matlab
1
5
7
sage: my_vector1 * my_vector2            # optional - matlab
75
sage: row_vector1 = matlab('[1 2 3]')             # optional - matlab
sage: row_vector2 = matlab('[3 2 1]')             # optional - matlab
sage: matrix_from_row_vec = matlab('[%s; %s]'%(row_vector1.name(), row_vector2.name()))     # optional - matlab
sage: matrix_from_row_vec                            # optional - matlab
1     2     3
3     2     1
sage: column_vector1 = matlab('[1;3]')               # optional - matlab
sage: column_vector2 = matlab('[2;8]')               # optional - matlab
sage: matrix_from_col_vec = matlab('[%s %s]'%(column_vector1.name(), column_vector2.name()))                                    # optional - matlab
sage: matrix_from_col_vec                            # optional - matlab
1     2
3     8
sage: my_matrix = matlab('[8, 12, 19; 7, 3, 2; 12, 4, 23; 8, 1, 1]')    # optional - matlab
sage: my_matrix                                      # optional - matlab
     8    12    19
     7     3     2
    12     4    23
     8     1     1
sage: combined_matrix = matlab('[%s, %s]'%(my_matrix.name(), my_matrix.name()))                                        # optional - matlab
sage: combined_matrix                               # optional - matlab
 8    12    19     8    12    19
 7     3     2     7     3     2
12     4    23    12     4    23
 8     1     1     8     1     1
sage: tm = matlab('0.5:2:10')                       # optional - matlab
sage: tm                                            # optional - matlab
0.5000    2.5000    4.5000    6.5000    8.5000
sage: my_vector1 = matlab('[1,5,7]')                # optional - matlab
sage: my_vector1(1)                                 # optional - matlab
1
sage: my_vector1(2)                                 # optional - matlab
5
sage: my_vector1(3)                                 # optional - matlab
7

Matrix indexing works as follows:

sage: my_matrix = matlab('[8, 12, 19; 7, 3, 2; 12, 4, 23; 8, 1, 1]')     # optional - matlab
sage: my_matrix(3,2)                                # optional - matlab
4

Setting using parenthesis cannot work (because of how the Python language works). Use square brackets or the set function:

sage: my_matrix = matlab('[8, 12, 19; 7, 3, 2; 12, 4, 23; 8, 1, 1]')    # optional - matlab
sage: my_matrix.set(2,3, 1999)                          # optional - matlab
sage: my_matrix                                         # optional - matlab
           8          12          19
           7           3        1999
          12           4          23
           8           1           1
class sage.interfaces.matlab.Matlab(maxread=100, script_subdirectory=None, logfile=None, server=None, server_tmpdir=None)

Bases: sage.interfaces.expect.Expect

Interface to the Matlab interpreter.

EXAMPLES:

sage: a = matlab('[ 1, 1, 2; 3, 5, 8; 13, 21, 33 ]')    # optional - matlab
sage: b = matlab('[ 1; 3; 13]')                         # optional - matlab
sage: c = a * b                                         # optional - matlab
sage: print c                                           # optional - matlab
    30
   122
   505
chdir(directory)

Change MATLAB’s current working directory.

EXAMPLES:

sage: matlab.chdir('/')          # optional - matlab
sage: matlab.pwd()               # optional - matlab
/
console()

x.__init__(...) initializes x; see help(type(x)) for signature

get(var)

Get the value of the variable var.

EXAMPLES:

sage: s = matlab.eval('a = 2') # optional - matlab
sage: matlab.get('a')               # optional - matlab
'     2'
sage2matlab_matrix_string(A)

Return an matlab matrix from a Sage matrix.

INPUT: A Sage matrix with entries in the rationals or reals.

OUTPUT: A string that evaluates to an Matlab matrix.

EXAMPLES:

sage: M33 = MatrixSpace(QQ,3,3)
sage: A = M33([1,2,3,4,5,6,7,8,0])
sage: matlab.sage2matlab_matrix_string(A)   # optional - matlab
'[1, 2, 3; 4, 5, 6; 7, 8, 0]'

AUTHOR:

  • David Joyner and William Stein
set(var, value)

Set the variable var to the given value.

strip_answer(s)

Returns the string s with Matlab’s answer prompt removed.

EXAMPLES:

sage: s = '\nans =\n\n     2\n'
sage: matlab.strip_answer(s)
'     2'
version()

x.__init__(...) initializes x; see help(type(x)) for signature

whos()

x.__init__(...) initializes x; see help(type(x)) for signature

class sage.interfaces.matlab.MatlabElement(parent, value, is_name=False, name=None)

Bases: sage.interfaces.expect.ExpectElement

set(i, j, x)

x.__init__(...) initializes x; see help(type(x)) for signature

sage.interfaces.matlab.matlab_console()

This requires that the optional matlab program be installed and in your PATH, but no optional Sage packages need be installed.

EXAMPLES:

sage: matlab_console()                # optional - matlab; not tested
                               < M A T L A B >
                   Copyright 1984-2006 The MathWorks, Inc.
...
>> 2+3

ans =

5

quit

Typing quit exits the matlab console and returns you to Sage. matlab, like Sage, remembers its history from one session to another.

sage.interfaces.matlab.matlab_version()

Return the version of Matlab installed.

EXAMPLES:

sage: matlab_version()    # random; optional - matlab
'7.2.0.283 (R2006a)'
sage.interfaces.matlab.reduce_load_Matlab()

x.__init__(...) initializes x; see help(type(x)) for signature

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