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How do you declare a symbolic function of time as a real variable

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Kevin Bachovchin
Kevin Bachovchin 2013-6-10
评论： Walter Roberson 2017-4-19
Hello,
I have several symbolic functions of time which I would like to declare as real. How can I do this?
syms x1(t) x2(t) x3(t) real
does not work because later when I say X = [x1 ; x2 ; x3], the expressions for X involve conjugates.
Thank you,
Kevin

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回答（2 个）

Walter Roberson
Walter Roberson 2013-6-10
You could try adding an assumption that imag(x1(t)) == 0
Azzi Abdelmalek
Azzi Abdelmalek 2013-6-10
syms t
x1=sin(t) % Example
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Kevin Bachovchin
Kevin Bachovchin 2013-6-10
The following code
syms x1(t) x2(t)
X = [x1(t) x2(t)]
diff(X,t)
yields [ diff(x1(t), t), diff(x2(t), t)]
The following code
syms x1(t) x2(t)
X = [x1(t) ; x2(t)]
diff(X,t)
yields
[ diff(conj(x1(t)), t)
diff(conj(x2(t)), t)]
Is there any way I can declare x1 and x2 so that I get
[ diff(x1(t), t)
diff(x2(t), t)]

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