Calling function with different variables

Question

Alexander Engman 2016-11-9

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/311357-calling-function-with-different-variables

评论： Alexander Engman 2016-11-9

采纳的回答： KSSV

在 MATLAB Online 中打开

Hi!

I have a function which looks like this:

function dZ=undervatten(n,x,Z)
p=[5.8795547370783 14.4873921534832 257.1922990416989];
c=4800+p(1)+((p(2))*2)+((p(3))*exp(-2));
q0=(c/cosd(n));
% Z(1):=avstånd
% Z(2):=vinkel
dZ=zeros(2,1);
dZ(1)=Z(2);
dZ(2)=-q0^2*(((-p(3)/1000)*exp(-Z(1)/1000))+p(2)/1000)/((4800+p(1)+(p(2)*Z(1)/1000)+(p(3)*exp(-Z(1)/1000))^3));
end

Then I want to be able to call this function for different values of n (which is in q0).

iter=1
for n=-10:14
[X,Z]=ode45(@undervatten,[0:3000],[2000 tand(n)]);
[value(iter)=Z(end,1)
iter=iter+1
end;

n represents starting angles for a sound wave, so basically I want to be able to call the function with angles from -10:14 degrees and then save the end value of Z in a vector, to see what values (depth) the different starting angles give after a certain distance (x). How can I change my code to be able to call different values of n for each iteration?

Thank you!

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Answer 1

KSSV 2016-11-9

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https://ww2.mathworks.cn/matlabcentral/answers/311357-calling-function-with-different-variables#answer_242576

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clc; clear all ;
n = -10:14 ;
X = zeros(length(n),90) ;
Z = zeros(length(n),90) ;
for i = 1:length(n)
    [x,z]=ode45(@undervatten,[0:3000],[2000 tand(n(i))]);
    X(i,:) = x ;
    Z(i,:) = z(:,1) ;
end;
function dZ=undervatten(n,Z)
p=[5.8795547370783 14.4873921534832 257.1922990416989];
c=4800+p(1)+((p(2))*2)+((p(3))*exp(-2));
q0=(c/cosd(n));
% Z(1):=avstånd
% Z(2):=vinkel
dZ=zeros(2,1);
dZ(1)=Z(2);
dZ(2)=-q0^2*(((-p(3)/1000)*exp(-Z(1)/1000))+p(2)/1000)/((4800+p(1)+(p(2)*Z(1)/1000)+(p(3)*exp(-Z(1)/1000))^3));
end

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Answer 2

Alexander Engman 2016-11-9

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/311357-calling-function-with-different-variables#answer_242586

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Thank you! I understand what I did wrong now.

Just one question, from where does the number 90 come from, in:

X = zeros(length(n),90) ;
Z = zeros(length(n),90) ;

?

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KSSV 2016-11-9

It is called initializing the variables.

Alexander Engman 2016-11-9

Yes I understand that you have to initialize it but what I am wondering is, how did you know that this number should be 90? What command is creating 90 columns in x and z?

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