Symbolic Toolbox Exponential Equations

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PB75
PB75 on 2 Apr 2020
Commented: Ameer Hamza on 6 Apr 2020
Hi Everyone
Getting started with symbolic tool box and live editor.
Trying to enter the below Wiebe Function equation using symbolic toolbox so i can find the derivative and build up the governing equations for the system.
However, getting stuck on simply entering the equation with the syms function, doh, as the e term has (t/td) to the power m+1, can you help with how i actually code this in the live editor so i can use and later solve for dxWiebe Function Equation
Thanks everyone.;-)
My attempt at creating x
syms x exp t t_d m
t_d = sym('t_d')
x = 1 - exp(-6.908*(t/t_d))^(m+1)

Answers (1)

Ameer Hamza
Ameer Hamza on 2 Apr 2020
Edited: Ameer Hamza on 2 Apr 2020
exp is a built-in function. Don't define it as a variable.
syms x t t_d m
x = 1 - exp(-6.908*(t/t_d)^(m+1));
dxdt = diff(x,t)
Result
dxdt =
(1727*exp(-(1727*(t/t_d)^(m + 1))/250)*(t/t_d)^m*(m + 1))/(250*t_d)
If you use live script, it will also render the equation to be displayed properly
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