Cant get the equation to work

Question

Clara Ghattas 2018-11-28

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/432468-cant-get-the-equation-to-work

关闭： MATLAB Answer Bot 2021-8-20

clc
num_values=11;    
first_val=0;
time=zeros(1,num_values);
z(1)=first_val;
s=zeros(1,11);
time(1)=first_val;
t=sym('t');
TU(1)=5*pi/180;
TU(2)=7*pi/180;
TU(3)=6*pi/180;
TU(4)=9*pi/180;
TU(5)=12*pi/180;
TU(6)=17*pi/180;
TU(7)=19*pi/180;
TU(8)=27*pi/180;
TU(9)=33*pi/180;
TU(10)=36*pi/180;
TU(11)=45*pi/180;
for n=2:11
    time(n)=(n-1)*15;
    z(n)=(-z(n-1)+((2*(TU(n)-TU(n-1)))/(time(n)-time(n-1))));
    sprintf('z= %.05f \n',z)
end
for n=2:10;
    s(n)=((z(n)-z(n-1))/(2*(time(n)-time(n-1)))) * ((t-time(n-1)).^2) + z(n-1)*(t-time(n-1))+TU(n-1);
end

Im trying to get the values from the equation with s using the values of the equation with z and i dont know how. In the workspaces it says that s is a 1x11 matrix but i think it should be 1x10

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Clara Ghattas 2018-11-28

even then, it says that the left and right sides have different number if elements so it cant work

Jan 2018-11-28

"it says" - who is it? Please post the complete error message, such that the readers do not have to guess, which line fails with which message.

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Answer 1

Areej Varamban Kallan 2018-12-7

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https://ww2.mathworks.cn/matlabcentral/answers/432468-cant-get-the-equation-to-work#answer_351022

编辑：Areej Varamban Kallan 2018-12-7

在 MATLAB Online 中打开

Hi Clara,

I have executed your code and the error message I get is "Unable to convert expression into double array". The variable 's' is defined to be a double matrix and the variable 't' is defined to be a symbolic variable. In the second for loop you are doing certain computations using the symbolic variable 't'. The results of such computations will be of symbolic type. As a result your code is attempting to assign a symbolic value to a double matrix. This is not valid.

Please redine s as:

s=sym(zeros(1,11));