MATLAB: Can I use ‘fplot’ with symbolic bounds

Symbolic Math Toolbox

I would like to plot a function between bounds defined by symbolic variables:

>> syms x y(x)
>> y(x) = 2*x^3;
>> xmin = sym(1);
>> xmax = sym(2);

Can I plot 'y(x)' between 'xmin' and 'xmax' using 'fplot'?

Best Answer

'fplot' does not support symbolic bounds, but you can convert the symbolic variables 'xmin' and 'xmax' to doubles (if they evaluate to a number, rather than a function) using the 'double' command:

https://www.mathworks.com/help/symbolic/double.html

Related Solutions

MATLAB: MeijerG function using MATLAB’s symbolic toolbox

As of R2017b, the function "meijerG" calculates the Meijer G-Function. This function can return either numerical values or symbolic expressions for the Meijer G-Function depending upon the input.

For 'double' inputs, "meijerG" returns a double, as shown below:

>> meijerG(3, [], [], [], 3)

ans =

6.4488

For 'sym' inputs, "meijerG" will return an exact symbolic answer whenever possible. An example is shown below:

>> meijerG(sym(2/5), [], sym(1/2), [], sym(3))

ans =

(2^(4/5)*3^(1/2)*gamma(1/10))/80

The documentation linked below has more details about "meijerG"'s full functionality:

https://www.mathworks.com/help/symbolic/meijerg.html

For prior releases, the symbolic MeijerG function is only available in MuPAD. From MATLAB, it must be evaluated using "evalin", as shown below:

>> y=evalin(symengine, 'simplify(meijerG([[3],[]], [[],[]],3))');

y =

9*exp(-1/3)

Once this command executes, 'y' will contain symbolic MeijerG function for given arguments.

Note that without the call to "simplify", an expression in terms of the MuPAD function "meijerG" may be returned, which will not be understood by MATLAB in further function calls. You can pass this back to "evalin" by first converting it with the "char" function, but this workflow is not recommended.

MATLAB: How to use ‘fplot’ with 2 variables which depend on a 3rd symbolic variable

You can achieve this by define 't' as symbolic variablePlease refer below code to achieve your task:

%% Symbolic solution
syms t
sinx=@(t)sin(t);
cosx=@(t)cos(t);
fplot(sinx,cosx);

Best Answer

Related Solutions

MATLAB: MeijerG function using MATLAB’s symbolic toolbox

MATLAB: How to use ‘fplot’ with 2 variables which depend on a 3rd symbolic variable

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