INVERSE OF A FUNCTION

Question

george veropoulos 2020-12-16

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/695825-inverse-of-a-function

评论： george veropoulos 2020-12-21

采纳的回答： Alan Stevens

HI i m looking for a script to inverse numericall a function

i use the function of inverse but not working because the functio is a liitle complicate

y=a*sin(x-ψ)+b*exp(-x/c) a,b,c are constand

thank you

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Alan Stevens 2020-12-17

在 MATLAB Online 中打开

The right-hand side of your expression will result in an infinite number of values of y, so there won't in general be a unique inverse value. However, if you know the range of values of x that you are interested in then you might be able to get a corresponding value for y using, say, the function fzero.

doc fzero

george veropoulos 2020-12-17

untitled.jpg

thank you for your reply

the x is angle from 0 to 180 degree

a graph of y is as follow

how i can use fzero ?

George

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Answer 1

Alan Stevens 2020-12-18

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https://ww2.mathworks.cn/matlabcentral/answers/695825-inverse-of-a-function#answer_579005

在 MATLAB Online 中打开

For a gven target value of y you could write a script along the lines of

x0 = initial guess;
x = fzero(@fn, x0);
function z = fn(x)
        a = ...
        b = ...
        etc.
        z = a*sin(x-psi)+b*exp(-x/c) - ytarget; 
end