Evaluate user input expression
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Hi, I was wondering if there is a way to evaluate complicated user input expression If 'a' and 'b' are vectors and if user input is 'a*b' or 'a*b^2', how do I evaluate the expression?
Thanks, Rupa
回答（2 个）
Walter Roberson
2017-1-15
1 个投票
If you read the expression as a string, then you can use symvar() to pull out the names of the variables the user used. You can then use exist() to test that each exists. Once you have done that, you can use vectorize() to convert * and / to .* and ./ . From there you could str2func and call that function passing in the values for the variables. Or you could eval()
dpb
2017-1-14
>> a=1:3;
>> v=input('Enter Matlab vector expression for a: ')
Enter Matlab vector expression for a: a.^2
v =
1 4 9
>>
Of course, this can be very dangerous...
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2017-1-14
2017-1-15
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