Hi, I want to use embedded matlab function to take a high accuracy derivative of a sin wave. I have used sine wave block from simulink library, with 101 samples per period, 0 offset, 1 amplitude and sample time of 0.01. The solver is configured as fixed step solver (ode 4) with the same step size of 0.01. The simulation time is set as 1 sec.
The sine signal is named as B and here is the code I am using in the embedded funciton block. The formula for the derevative that I want to use uses central difference technique and is as follows.
B'(n))=(-B(n+2)+8B(n+1)-8B(n-1)+B(n-2))/(12.*step size); where, B is the input signal, n is the current time step I have successfuly tested the formula using command line and script and it is working, but when I use the same code in embedded matlab function, I get out of bounds error.
Here is the code that I am using:
function D = fcn(B) D=zeros (101,1); for n=3:99 D(n)=(-B(n+2)+8.*B(n+1)-8.*B(n-1)+B(n-2))./(12.*0.01); end This is the error message that I receive: Runtime error: Index into array out of range Attempted to access 5 element of data B. The valid index range is 1 to 1. I think it is due to the signal size problem, but I dont know how to fix it. Please help me, I will really appreciate you help! Thanks
