How to find the x value of a function given by points?

tinterval=[0:0.001:40]; %sec
acc=3;
w0=30;
Wspeed=acc*tinterval+w0;
tetae=Wspeed.*tinterval;

tetaeFract=rem(tetae,360);

I need to find the tinterval value when tetafract is equal to 60, and I need this as a value to use later in the script, I don't need it graphically.

Thank you in advance.

Answer 1

[Dyuman Joshi]

Use logical indexing - Find Array Elements That Meet a Condition

Also, as you are working with floating point numbers, it would be better to compare using a tolerance.

[Davide Cannavacciuolo]

Yes thank you I think is the way, indeed the value i need is 60 but in the array there is 60.009 how can i use the tolerance to find that index?

[Dyuman Joshi]

tinterval=[0:0.001:40]; %sec
acc=3;
w0=30;
Wspeed=acc*tinterval+w0;
tetae=Wspeed.*tinterval;

tetaeFract=rem(tetae,360);

%Define a tolerance
tol = 0.01;

idx = abs(tetaeFract - 60) < tol;

tetaeFract(idx)

ans = 1×4

59.9918 60.0058 60.0090 59.9960

new_values = tinterval(idx)

new_values = 1×4

1.7080 11.8820 24.7490 28.5410

Shouldn't 60.0058 be a better fit than 60.009?

[Davide Cannavacciuolo]

yes perfect thank you very much!

[Dyuman Joshi]

You're welcome!