pllllllllllllZzz ..... I need it today ;(

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mon mon
mon mon 2011-10-26
*Hi evry body :)
can U help me to answer qustion num(c)? I don't Know how can i answer it :( PlZz help me =,(*
Exercise 2:
(a) Write an m-file named cosmx.m (“COS Minus X”) that defines the function:
(x) = cos x - x
Recall that a function m-file is one that starts with the word function. In this case it should start off as
function y = cosmx ( x )
% y = cosmx(x) computes the difference y=cos(x)-x
% your name and the date
y = ???
(This is very simple(the object of this exercise is to get going.)
(b) Now use your cosmx function to compute cosmx(1). Your result should be about -0.4597.
(c) Now use your cosmx function in the same plot sequence as above to plot cosmx and the horizontal axis on the interval -π < x < π. Hint: The horizontal axis is the line y = 0.
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Daniel Shub
Daniel Shub 2011-10-26
Great, so show us the function and then show us what you have done for part c.
mon mon
mon mon 2011-10-26
a)
function y = cosmx ( x )
%y = cosmx(x) computes the difference y=cos(x)-x
% Name & Date
y =cos(x)-x;
end
b) in command window :
cosmx(1)
and it give me the correct result -0.4597

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采纳的回答

mon mon
mon mon 2011-10-26
plZz help me =,(
  2 个评论
Image Analyst
Image Analyst 2011-10-26
How generous of you to accept your own "answer" instead of someone else who helped you.
Daniel Shub
Daniel Shub 2011-10-26
I think he may have accepted his answer prior to getting any help (with the possible exception of Amardeep's answer). It was accepted before I got involved.

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更多回答（4 个）

Daniel Shub
Daniel Shub 2011-10-26
ohhh, I know the answer ...
function y = cosmx ( x )
% y = cosmx(x) computes the difference y=cos(x)-x
% your name and the date
y = randn(size(x));
y(x == 1) = -0.4597;
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mon mon
mon mon 2011-10-26
Thanks Daniel ,
But it give me an Error ,too. =(
Daniel Shub
Daniel Shub 2011-10-26
@mon mon, you are right, I made a mistake. It should work now.

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Amardeep
Amardeep 2011-10-26
Create a function which calls cosmx which should look something like. I have left out the plotting functions and the variable arraying to create plottable data.
x = -pi
while x=< pi
y=cosmx(x)
x=x+0.01 (or whatever division resolution you want along the x axis)
end
That should be more than enough to get you along the right lines for part c.
mon mon
mon mon 2011-10-26
my Answer in part (a)
function y = cosmx ( x )
%y = cosmx(x) computes the difference y=cos(x)-x
% Name & Date
y =cos(x)-x;
end
Then part (b) I wrote in command window cosmx(1)
It give me correct >>>> -0.4597
but I do not know part(c) =(
  2 个评论
Daniel Shub
Daniel Shub 2011-10-26
If I asked you to evaluate cosmx at -pi, 0, and pi, how would you do that. What about if I asked you to evaluate cosmx between -pi and pi with steps of 0.01. Do you know how to plot anything?
try
doc plot
mon mon
mon mon 2011-10-26
Daniel
Thank U very much .. =)
I do it .. <3

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mon mon
mon mon 2011-10-26
Thanks All .. =)

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