Asking for user input only once with input, or take values like pi/3 with inputdlg

I have a function that calculates when you input values for n, for x, for y. Now I need to ask the user for input. I prefer how inputdlg asks for input so I wrote the following (where seriessum is my function, written in another .m file):

a=inputdlg({'Enter a value for n', 'Enter a value for x', 'Enter a value for y'}, 'ΣS=(x/y).^i, for i=1:n')
a1=zeros(1,3);
for k=1:3
    a1(k)= str2double(cell2mat(a(k))); %takes the cell array and converts it into a regular array and then the string into an integer
end
seriessum(a1(1),a1(2),a1(3))

This works for most inputs, however, I realised it doesn't work for inputs like 'pi/4' or similar.

That's when I decided that I would use a regulat input function and wrote:

promptn = 'Enter an integer value for n';
promptx = 'enter a value for x';
prompty= 'Enter a value for y';
n = input(promptn)
x = input(promptx)
y = input(prompty)
seriessum(n, x, y)

But in this case, the prompts keep appearing in the workspace (I mean: I enter a value for n, for x and for y, and I'm immediately asked to enter a value for n again).

I would like to know if I can fix any of this issues. The second issue is more of an inconvenience because it does calculate the sum anyways.

Answer 1

[ME]

When you use the inputdlg function and input something like pi/4 it appears to save everything as a cell array of strings. You can always use str2num() to convert the string back into a numerical form - see the below example copied directly from my command window.

a =

  3×1 cell array

    {'pi/4'}
    {'pi/3'}
    {'pi'  }

>> a{1}

ans =

    'pi/4'

>> str2num(a{1})

ans =

    0.7854