Matlab ode45 referencing past value

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    Matlab Ode45 Value
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SUMMARY

The discussion focuses on using MATLAB's ode45 function to reference past values in a differential equation. The user, rsc42, successfully implemented a solution by defining Y(3) as the difference between current and past values of Y(1) and Y(2) at specific time steps. The equation used is Y(3) = Y(ceil(t),1) - Y(ceil(t-30),1) + Y(ceil(t),2) - Y(ceil(t-30),2), which effectively captures the desired past value reference. This approach allows for the integration of historical data into the ode45 calculations.

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  • Understanding of numerical methods for solving differential equations
  • Knowledge of the ode45 function and its parameters
  • Basic concepts of time series data manipulation
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This discussion is beneficial for MATLAB users, particularly those working with numerical simulations, engineers modeling dynamic systems, and researchers needing to incorporate historical data into their differential equations.

yoshig
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I am using ode45, but have a value that is based upon its own past values. I want to be able to include a parameter that equals (y(3) at time t) - (y(3) at time (t- 30days)). Is there a way to include this using ode45?
Thank you in advance!
 
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Could you post some equations to clarify?
 
Thanks rsc42,

I have actually figured out what I was looking for. I used Y(3) = Y(ceil(t),1) - Y(ceil(t-30),1)+Y(ceil(t),2)-Y(ceil(t-30),2)). This is because my steps are in increments of 1, and I wanted to subtract past values of y1 and y2.
 

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