plotting function which contain zero denominator term
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I have a function : 
. I need to plot a graph between x Vs g(x) where
. I need to plot a graph between x Vs g(x) where 
, I just need values of x from o to ∞ without x=1 because it will give me 
which doest not make sense. My Question: How can I use "if and elseif" syntax to plot grap between x Vs g(x) excluding value x=1 and inclusing rest of others.
5 个评论
Walter Roberson
2021-1-29
g(x) is infinite or undefined because f(1) is infinity . How would you plot a graph "between" something and an infinite or undefined value?
shree thapa
2021-1-29
shree thapa
2021-1-29
Walter Roberson
2021-1-29
Okay, so suppose I choose x = 7. Then what would the expected plot be? 
is constant because the integral "uses up" all of the unbound variables in f(x)
is constant because the integral "uses up" all of the unbound variables in f(x)
shree thapa
2021-1-29
回答（1 个）
syms x
f(x) = 1/(1-x^2)
g(x) = int(f(x), x, 0, inf)
g(x) is always undefined, no matter what the value of x is.
ratio = f(x)/g(x)
fplot(ratio, [0 20])
Notice the plot is empty. Because every entry is NaN.
1 个评论
syms x
f(x) = piecewise(x < 1, 1/(1-x^2), x == 1, 0, -1/(1-x^2))
a = int(f(x), x, 0, 1)
b = int(f(x), x, 1, inf)
a+b
g(x) = int(f(x), x, 0, inf)
ratio = f(x)/g(x)
fplot(ratio, [0 20])
So you can define away the integral so that you do not get nan (by integrating a different function), but you are stuck with the problem that g(x) is constant.
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2021-1-29
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