Converting a string containing a function (t) to a useable variable.
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I'm using inputdlg to take user input and calculate and store the value.
This is what I was trying to do.
x = inputdlg('Enter Mathematical Equation')
t = [0:0.001:20]
z = str2double (x{1})
I need to be able to enter 20*cos(4*t) for instance and have the calculated result stored in the variable, but I can't seem to get any result or for matlab to recognize the variable entered even if its declared prior to the inputdlg. Simply arguments like 20*cos(20) properly converts and calculates. How would I go on about being able to use the function from the string.
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dpb
2018-8-22
Need to convert string to the function---
>> t=0:pi/8:pi; % predefined t
>> s='20*cos(4*t)'; % sample input string
>> s=vectorize(['@(t)' s]) % convert to allowable functional form and vectorize expression
s =
'@(t)20.*cos(4.*t)'
>> fn=str2func(s) % now create the function handle variable
fn =
function_handle with value:
@(t)20.*cos(4.*t)
>>
>> z=fn(t) % use it with existing t
z =
20.0000 0.0000 -20.0000 -0.0000 20.0000 0.0000 -20.0000 -0.0000 20.0000
>> fn(0) % or with some other input, constant or variable ok...
ans =
20
>>
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