Accessing variables with functions in Matlab

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Richard Miller 2018-3-13

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编辑： Stephen23 2018-3-13

Suppose that I defined something in a .m file such as an initial velocity and I want to do a RK4 method to find numerical solutions for the velocity as time progresses. So, I define a function using the line: 'function RK4 = Runge_Kutta4()'.

In python, a function like this (e.g. RK4 = Runge_Kutta4()) would have access to the initial velocity, but could not change the variable. For my function to change the variable I would need to have the function call the variable using the line: 'RK4 = Runge_Kutta(Velocity)'. Is this true for Matlab as well?

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Stephen23 2018-3-13

编辑：Stephen23 2018-3-13

" Is this true for Matlab as well?"

Forget everything you know about Python's scoping rules, they have no relevance to MATLAB at all. In terms of what the user sees, MATLAB is entirely pass by value: what happens in Vegas stays in Vegas!

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Answer 1

James Tursa 2018-3-13

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https://ww2.mathworks.cn/matlabcentral/answers/388081-accessing-variables-with-functions-in-matlab#answer_309890

编辑：James Tursa 2018-3-13

在 MATLAB Online 中打开

To have a function change a variable in MATLAB, one would typically do this:

x = myfunction(x);

And then the body of myfunction would change the value of x.

Another way is to use nested functions. E.g., if x is in a function and myfunction is a nested function within that first function, then myfunction could change x directly.