How to transform function in MatLab? Shift, Scale etc.

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ha9981 2012-9-23

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评论： Preetha Thanunathan 2020-4-7

If I have a function as follows:

syms x1;
syms t;
x1 = exp(t)* Heaviside(2*t);

How do I do define x2 = x1(t-2) so I can plot it. I would rather not have to redefine the entire function doing the work myself each time I want to do a transformation. Is there a way of achieving this?

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Preetha Thanunathan 2020-4-7

I have a function f(x) whose range is the interval [0, 1], and I need to shift it and stretch it so that the range is now the interval [a, b]. Find a function g(x) (defined in terms of f(x)) so that g(x) has an range [a, b].

In Matlab, the rand command produces a random number between 0 and 1, under the uniform distribution; that's different from the normal distribution. The graph of the uniform probability distribution is a horizontal line. The graph of the normal distribution is the bell curve.

I need a program that will accept input values a and b, a < b, and will output a random number between a and b, You'll do this by shifting and stretching the rand function. Notice that in Matlab the rand function doesn't take an input. You just type rand and hit enter, and the program will spit out a random number between 0 and 1.

can anyone answer this question

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Answer 1

ha9981 2012-9-23

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http://www.mathworks.com/help/symbolic/subs.html

I think I found it. Appears to work.

x3 = subs(x1, t, t-2)

Is this a correct and reliable way?

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Wayne King 2012-9-23

ahh yes, I forgot about subs!

Azzi Abdelmalek 2012-9-23

编辑：Azzi Abdelmalek 2012-9-23

If you want to delay with t0, compute x(t) then plot(t+t0,x)

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Answer 2

Wayne King 2012-9-23

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编辑：Wayne King 2012-9-23

在 MATLAB Online 中打开

I don't know of a shift operator for symbolic functions.

   syms t
   tprime = t-2;
   x1 = exp(t)*heaviside(2*t);
   x2 = exp(tprime)*heaviside(2*tprime);

Or just:

x2 = exp(t-2)*heaviside(2*(t-2));

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Wayne King 2012-9-23

I'm not sure what you mean by recheck your code.

ha9981 2012-9-23

You fixed it now. It said xprime before so it wasn't going to work.

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Answer 3

Azzi Abdelmalek 2012-9-23

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编辑：Azzi Abdelmalek 2012-9-23

在 MATLAB Online 中打开

syms t x
x1 = exp(t)* heaviside(2*t);
t=0:.1:10
if you want to plot |x1(t-2)| then
y=eval(x1)
t=t+2  % not t=t-2  because it's a delay 
close;plot(t,y)
set(gca,'xlim',[0 max(t)])