I have an iteration code which I am using to find latitude/longitude of a set of heights (h_intercept). This is a 1x79 matrix.
It works perfectly until the 22nd value. I've found that this is when h_test>h_intercept. I tried to put a condition in to reset it but it doesn't work.
When h_test>h_intercept, all of the range values become zero
For example
for j=20:40
rng_sat= sat_look_tcs_pass1(3,j);
u_sat=[sat_look_tcs_pass1(1,j)/sat_look_tcs_pass1(3,j);sat_look_tcs_pass1(2,j)/sat_look_tcs_pass1(3,j);sat_look_tcs_pass1(3,j)/sat_look_tcs_pass1(3,j)];
h_intercept=sat_look_pass1_llh(3,j)/2e3;
h_test=zeros(1,3);
rng_test_min=0;
rng_test_max=rng_sat/2e3;
err=0.01;
while abs(h_intercept-h_test)>err
rng_test=(rng_test_min+rng_test_max)/2;
tcs_test=u_sat*rng_test;
llh_test=tcs2llhT(tcs_test,station_llh);
h_test=llh_test(3,:);
if h_test>=h_intercept
rng_test_max=rng_test;
else
rng_test_min=rng_test;
end
end copter_llh(:,j)=(llh_test); h_interceptloop(:,j)=(h_intercept); end % code end
Any suggestions appreciated!
I think the error is in the first loop. In the first line you choose values 60 to 79:
h_intercept=sat_look_pass1_llh(3,60:79)/2e3;
However, you only use the length of that vector and not its values in the following code.
You iterate over the length of h_intercept, i.e. from 1 to 19:
for j=1:length(h_intercept)
which means that h_intercept=sat_look_pass1_llh(3,j)/2e3; will get the wrong value, as j ranges from 1 to 19 and not from 60 to 79.
If you change your for loop to for j=60:79, it should work ( and you can also delete the first line h_intercept=sat_look_pass1_llh(3,60:79)/2e3; )
Related
I have been thinking about how to create an array that grows at a regular interval of time (for instance every 5 seconds) on Matlab.
I figured out 2 ways, either using tic/ toc or timer function. Later this program will be complexified. I am not sure which way is the best but so far I am trying with using timer.
Here is what I have tried :
clc;
period=5;%period at which the file should be updated
freq=4;
l=freq*period;
time=[0];
a = timer('ExecutionMode','fixedRate','Period',period,'TimerFcn',{#time_append, time,l,freq},'TasksToExecute',3 );
start(a);
function [time]=time_append(obj,event,time,l,freq)
time_append=zeros(l,1);
last_time=time(end)
for i=1:1:l
time_append(i)=last_time+i/freq;
end
time=[time;time_append];
end
After compiling this code, I only get a time array of length 1 containing the value 0 wheras it should contain values from 0 to 3x5 =15 I think it is a stupid mistake but I can't see why. I have tried the debug mode and it seems that at the end of the line time=[time;time_append], the concatenation works but the time array is reinitialised when we go out of the function. Also I have read that callback function can't have output. Does someone would know how I could proceed? Using globals? Any other suggestion?
Thank you for reading
You can do this by using nested functions. Nested functions allow you to access "uplevel variables", and you can modify those. Here's one way to do it:
function [a, fcn] = buildTimer()
period=5;%period at which the file should be updated
freq=4;
l=freq*period;
time=0;
function time_append(~,~,l,freq)
time_append=zeros(l,1);
last_time=time(end);
for i=1:1:l
time_append(i)=last_time+i/freq;
end
time=[time;time_append];
end
function out = time_get()
out = time;
end
fcn = #time_get;
a = timer('ExecutionMode','fixedRate',...
'Period',period,...
'TimerFcn',{#time_append,l,freq},...
'TasksToExecute',3 );
start(a);
end
Note that the variable time is shared by time_append and time_get. The timer object invokes time_append, and updates time. You need to hand out the function handle time_get to retrieve the current value of time.
>> [a,fcn] = buildTimer; size(fcn()), pause(10); size(fcn())
ans =
21 1
ans =
61 1
I can find / identify all digits in a number using a recursive function.
My issue is trying to sum the number through each recursion.
I had to initialize sum = 0 at the top of my function statement, and when I return through recursion, I'm always resetting sum back to zero. I do not know how to save a variable without first initalizing it.
Code is below;
function output= digit_sum(input)
sum=0
if input < 10
output = input
else
y=rem(input,10);
sum=sum+y
z=floor(input/10);
digit_sum(z)
end
output=sum
end
I want to use structure in matlab but in first iteration it's run correctly and in other iteration give that message .
1x2 struct array with fields:
my code is :
for i=1:lenfd
currow=rees(i,:)
maxcn=max(currow)
if maxcn~=0
maxin=find(currow==maxcn)
ress(i).x =maxin
end
end
thank you.
That message is not a warning or error. That's just MATLAB printing the output of an operation. And it does that by default, unless you suppress it by appending a semicolon to the command:
for ii = 1:lenfd
currow = rees(ii,:); % <=== NOTE: semicolons at the end
maxcn = max(currow);
if maxcn ~= 0
ress(ii).x = find(currow==maxcn);
end
end
Note that max() may have 2 outputs, the second output being the first index into the array where the maximum occurred. If you know beforehand that any maximum will occur only once, you can skip the call to find() and use the second output of max().
I would like to have a for loop with 1:25 range but I do not want the for loop to go through number 23 in that range
in another format; I want it like this 1:22 24:25
is it doable this way?
please help
Yes. You can write:
for num = [1:22 24:25]
% do something with num
end
Another solution:
for idx=1:25
if idx==23, continue, end
disp(num2str(idx));
end
Just to add an alternative:
skip = [23];
for idx = 1:25
if ~any(idx == skip)
%// Your code here
end
end
I think it's more readable than using [1:22 24:25] as your loop variable as you can see clearly and quickly which numbers are being skipped (unless [1:22 24:25] is a variable getting generated elsewhere in which case I would go with that method), it avoids continue which is controversial and it's easy to add other numbers to skip (i.e. skip = [7, 18, 23] etc...)
the program is working perfectly but when i am changing it to function the follwing error is beeing displayed:
[Parent1index, Parent1Position, alldcel] = Parent1n(TotalnoOfGrids, noOfNodes, Penalties, test)
??? Index exceeds matrix dimensions.
Error in ==> Parent1n at 10
[~,index]=min(alldcel{t});
Because alldcell{t} may not exist for some values of t if the condition to assign values to it in
if Penalties{t}(r)== 0;
alldcel{t}(r)=inf;
end
is never satisfied. Assume for some t that all values of Penalties{t} are different than zero. Then you would never assign inf to alldcell{t}. That means, you are only extending the cell array alldcell when Penalties{t} is zero for some r. If the condition is never satisfied, alldcell{t} will not exist and asking for it will give you a cell array error.
You should at least initialize it using alldcell = cell(TotalnoOfGrids,1).
Also, comparing for equality to zero using a==0 is not a good idea. You should use abs(a)<tol for some small value tol.
ok with this code the functiion worked:if Penalties{t}(r)> 0;
alldcel {t}(r)=alldcel{t}(r);
else alldcel {t}(r)=inf; but interchanging if statement with else did not