solving a linear ODE

how to write in matlab

y = e^ int(75/80)dt

[James Tursa]

Please provide more detail. What differential equation are you trying to solve?

[Brenda Galabe]

d dtx1(t) = − x1(t) 2 + 20 d

solved using linear DE equation to get

y = exp^int(1/2)dt ** not 75/80

[James Tursa]

Is it this? (where x1 is a function of time)

d(x1)/dt = -x1 / 2 + 20 * d

What is that d at the end?

[Brenda Galabe]

sorry no d so just

d(x1)/dt = -x1 / 2 + 20

[Stephan]

Hi Brenda,

i saw that you got some answers on your severa questions here in the forum. Did you notice that you can accept and/or vote for answers, in order to thank the volunteers here for taking the time to help you with your problems?

Answer 1

[madhan ravi]

You can verify the result with wolfram but here you will see a C which is constant which arises after antiderivative(without limits):

syms y(t)
ode=diff(y) == exp(75/80)
dsolve(ode)

[Brenda Galabe]

what about the exponential before the integral how to represent that

[madhan ravi]

exp() see edited answer

[madhan ravi]

This is how you write the equation:

syms t y
eqn = y == vpa(exp(1)^(int(75/80,t))) % in decimal form
eqn = y == exp(1)^(int(75/80,t))      % in fractions form

[madhan ravi]

Brenda Galabe's answer moved here for consistency:

but the equation looks like this

y = exp^int(75/80)dt . so the exp is before the integral

[madhan ravi]

see https://in.mathworks.com/matlabcentral/answers/435252-solving-a-linear-ode#comment_649743

[madhan ravi]

Brenda Galabe's answer moved here for consistency:

ok cool. answer im getting is

eqn =

y == (3060513257434037/1125899906842624)^((15*t)/16)

i know on paper answer suppose to be exp^(75/80)t

[madhan ravi]

Basically they are the same but represented in different forms just substitute the values and see as below:

>> t=1;
>>  exp(1)^(75/80)*t 

ans =

    2.5536

>> (3060513257434037/1125899906842624)^((15*t)/16)

ans =

    2.5536

>> 

[madhan ravi]

Brenda Galabe's answer moved here for consistency:

ok thank you

[madhan ravi]

Anytime :)

Answer 2

[Brenda Galabe]

not sure what that means

[madhan ravi]

upload the photo of that equation