listlib::insertAt will not work in script

Hi there. I am trying to add a zero at the top of my vector so i can minus one vector from the other. Stating the reason may help... I have to work out the displacement of a spring. I am using the equation F=k/x, however, the true equation i need is F=k/(x-y), with y being the displacement of the spring from the original position as it increases the force if it is at a different position. I have looked through lots of the answers on here in regard to adding an element to a vector and subtracting the difference between 2 elements in a vector however diff() was giving the wrong answer and i was also having problems with vector sizes not being equal. The code i have at the moment is attached. This is not a homework problem it is part of my dissertation. Also if anyone can see anything that would slow it down i would be grateful as all of my matlab is self taught. Many Thanks

Answer 1

[Walter Roberson]

listlib::insertAt is only for use in MuPAD.

[Ross Hanna]

Hi there. I worked out from the documentation that it was only for MuPAD. I guess i should have been clearer with my question. I have now updated it to say that what i would like to know is if there is an equivalent function for use in scripts, another way to code the same thing or if there is something in the maths/physics that i am missing/ made a mistake in. Sorry for the ambiguity.

[Walter Roberson]

You need to discuss more why you say that "diff was giving the wrong answer".

diff(x) for vector x is the equivalent of x(2:end)-x(1:end-1)

To put a 0 at the beginning of a vector use either

[0, TheVector]

or

[0; TheVector]

depending on whether it is a row or column vector.