- #1
Pythagorean
Gold Member
- 4,401
- 313
I'm having a helluva time trying to build the index for this code.
First of all, this is homework, I'll admit, but I've done all I could
to research the problem on my own, so I understand the question I'm trying to ask by now, but I still haven't found an answer
Basically, I'm modeling Radioactive Decay in several different ways on
one plot. The issue I'm having is with the Euler method, because it's a numerical approach, and the last three years of my college life has been studying continuous.
Also, I have to use a while loop.
here is the code, followed by my question:
%----------------------------------------------------------------
%EULER
%----------------------------------------------------------------
i=1
t(1)=0
Ne(1)=100
while t>=ti & t<=tf %<---tf and ti are previously defined
t(i)=delt*(i-1)
Ne(i+1)=(1-lam*delt)*Ne(i)
i=i+1
end
plot(t,Ne,'ro')
------------------------------------------------------------------
Before plot even comes on, I can see that Ne will have one more
value than t does, and when I run it (when I run it, it says the matrices must must have an equal amount of elements and such, and if I scroll
through the run, i can see that Ne has (as I assumed) one more value
than t.
So I try plot(t,Ne(i-1),'ro'), hoping it will return to the whole indix set one period ago for Ne, but no, it just takes the scalar of Ne at the i-1 index and gives me a nice flat line.
Question: How do I cut off the end of the matrices (Ne and t) to the same length like a paper cutter does with paper
OR
How do I enter a final value for one last indice after the loop has created a table (this would go after the 'end' of the loop and before the 'plot'.
First of all, this is homework, I'll admit, but I've done all I could
to research the problem on my own, so I understand the question I'm trying to ask by now, but I still haven't found an answer
Basically, I'm modeling Radioactive Decay in several different ways on
one plot. The issue I'm having is with the Euler method, because it's a numerical approach, and the last three years of my college life has been studying continuous.
Also, I have to use a while loop.
here is the code, followed by my question:
%----------------------------------------------------------------
%EULER
%----------------------------------------------------------------
i=1
t(1)=0
Ne(1)=100
while t>=ti & t<=tf %<---tf and ti are previously defined
t(i)=delt*(i-1)
Ne(i+1)=(1-lam*delt)*Ne(i)
i=i+1
end
plot(t,Ne,'ro')
------------------------------------------------------------------
Before plot even comes on, I can see that Ne will have one more
value than t does, and when I run it (when I run it, it says the matrices must must have an equal amount of elements and such, and if I scroll
through the run, i can see that Ne has (as I assumed) one more value
than t.
So I try plot(t,Ne(i-1),'ro'), hoping it will return to the whole indix set one period ago for Ne, but no, it just takes the scalar of Ne at the i-1 index and gives me a nice flat line.
Question: How do I cut off the end of the matrices (Ne and t) to the same length like a paper cutter does with paper
OR
How do I enter a final value for one last indice after the loop has created a table (this would go after the 'end' of the loop and before the 'plot'.