matlab_wrapper

MATLAB Wrapper allows use of MATLAB scripts and functions in the context of an OpenMDAO 1.x Problem. There are two types of MATLAB scripts that can be integrated: Function Files and Bare Files. The MATLAB Wrapper determines the type by examining the script file.

Currently, only MATLAB version 2015a and later are supported.

Function Files

In a Function File you define a function with the same name as the script filename and this becomes the entry point for the script. There are a few restrictions in the current implementation:

• Only scalar (double) type values are allowed as inputs and outputs.
• There can be more than one function declared in the script, but the wrapper will only use as an entry point the function with the same name as the script filename. This name is case-sensitive and must match exactly.

Below is a Function File example of a MATLAB Wrapper script:

function [sum, product] = Example(x, y, z)
sum = x + y + z
product = x * y * z
end

Bare Files

In a Bare File you define the inputs and outputs of the script by a set of specially-formatted comments at the beginning of the file. These comments allow you to define the data type of all the inputs and outputs.

Below is a Bare File example of a script that doubles a number of different types of inputs:

% variable: output1 double output
% variable: output2 double[] output
% variable: output3 string output
% variable: output4 string[] output
% variable: input1 double input
% variable: input2 double[] input
% variable: input3 string input
% variable: input4 string[] input

output1 = input1 * 2
output2 = input2 * 2
output3 = strcat(input3, input3)
output4 = [input4, input4]

You cannot define functions in a Bare File style MATLAB integration file; however, you can call other function files that you have defined.

MATLAB Data Type Conversion

Since the data passed between Components is managed by Python, the table below describes the conversions that occur when data is passed into or out of a MATLAB Wrapper Component.

Python	to MATLAB	to Python
Boolean	Logical	Boolean
Int	N/A [1]
List of Ints	N/A [1]
Numpy Int Array	Double Array	Numpy Float Array [2]
Float	Double	Float [3]
List of Floats	N/A [1]
Numpy Float Array	Double Array	Numpy Float Array
String	N/A [1]
List of Strings	Cell Array of Strings	List of Strings
Numpy Array of Strings	N/A [1]
Unicode	Char	Unicode
List of Unicodes	Cell Array of Unicodes	List of Unicodes
Dictionary	Struct	Dictionary [4]

[1]	(1, 2, 3, 4, 5) These types are not allowed to be passed into MATLAB Wrapper Components.

[2]	Integers in an array will be converted to floats upon passing through a MATLAB Wrapper Components.

[3]

All doubles in MATLAB are essentially a one-by-one array (1x1), so the framework automatically unwraps all one-by-one arrays to a single float value as they are passed to the next analysis Component. E.g. A 1x1 Numpy Array will become a double in MATLAB and will result in a double in OpenMDAO when it is passed to the next analysis Component.

[4]

Structs in MATLAB can only accept fieldnames that meet the following three criteria: Start with a letter Contain only letters, numbers, and/or the underscore character Must be no longer than namelengthmax (currently 63) characters Although Python can handle arbitrary strings as the keys in dictionaries, you must meet these criteria if you are going to pass the dictionaries to a MATLAB Wrapper Component.