Plotting of an inline function

    str=input('Give an equation in x\n','s');
    f=inline(str,'x');

I want to plot a graph of the function 'f'. I tried fplot but it is not working. How can I plot 'f' vs. 'x'.

[madhan ravi]

Can you give an example of your input by copying every results from the command window?

[Sahil Khan]

>> Untitled
Give an equation in x
x^2-3
>>

Copied from command window

[Stephen23]

@Sahil Khan: can you please explain why you are using a very outdated and almost obsolete inline function? The inline documentation clearly states "inline will be removed in a future release. Use Anonymous Functions instead." Do you have a reason why you cannot use (much better) function handles for this task?

[Sahil Khan]

I wasnt exactly up to date with that. I am learning MATLAB and started three days before. Can you please elaborate the other method ?

[Stephen23]

@Sahil Khan: follow the bold blue link in my comment.

[madhan ravi]

@stephen cobeldick I have a question . I am using matlab 2017a but str2sym command is not working for me . Any reason/s?

[Stephen23]

@madhan ravi: did it work before? Do you have a license for that toolbox?

[madhan ravi]

What toolbox is required for this? Yes @stephen but suddenly it says undefined function same for sprint as well but sprintf and fprintf commands work don’t know why :/

[Stephen23]

"What toolbox is required for this?"

Use an internet search engine to find this page:

https://www.mathworks.com/help/symbolic/str2sym.html

Read the text in the top left corner of that page:

Symbolic Math Toolbox

Use an internet search engine to search for "MATLAB what toolbox licenses do I have"

... etc

[madhan ravi]

Thank you @stephen and sorry

Answer 1

[Stephen23]

You should use str2func to create an anonymous function:

str = input('Give an equation in x: ','s');
fun = str2func(sprintf('@(x)%s',str));
fplot(fun,[0,10])

And tested:

>> str = input('Give an equation in x: ','s');
Give an equation in x: sqrt(x)-x
>> fun = str2func(sprintf('@(x)%s',str));
>> fplot(fun,[0,10])

Answer 2

[Star Strider]

See: how do you user input a equation in matlab ? i used inline function but unable to plot the equation. suppose i want my input equation as x-cos(x). and than plot it. how do i do it? Is the following code correct ? (link). This seems to be the same homework problem!