Indexing a variable value
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I have been given an assignment where we basically have to run a simulation for a rocket launch. In part of this, we have to calculate the density of the atmosphere at the height of the rocket so that we can calculate the drag force. The heights of the rocket (in increments of one kilometre) have been given to us in column one of an excel sheet, with their respective density values alongside them in column 2 (stored in a file called DensityData) I have already read in these values using xlsxread.
To simulate the launch, we have used a for loop for time. However, I am trying to write a subscript for a function that will produce the density value for each iteration of the for loop. I attempted to write the function as
function [density] = findDensity(DensityData.m) %g/cm^3
%DensityData : returns the density of the atmosphere
%This uses the altitude of the rocket to produce a value for the density of
%the atmosphere at that height
[density] = DensityData(position,1);
but this produces an error as it won't let me enter a non-numerical or non-logical value for the row value in the index, i.e. position.
If anybody could help me find an alternative way around this, that would be much appreciated!
P.s. the heights are in increments of 1 km so a round function may also have to be used on the position value before using it for any code similar to the above.
Aoi Midori on 3 Dec 2018
Do you want to calculate the density values using the function DensityData() or do you already have the density values calculated and the matrix DensityData where it contains the heights in column 1 and the density values in column 2? In the latter case, this could be one of the solutions.
function [density] = findDensity(DensityData, position)
[density] = DensityData(position,2);