# Geoff

I use MATLAB for small jobs and C++ for real jobs.

Professional Interests: Problem solving

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**Content Feed**

HOW CAN I CALCULATE THE SIGNAL TO NOISE RATIO(SNR) OF A CHIRP SIGNAL

From Wikipedia: http://en.wikipedia.org/wiki/Signal-to-noise_ratio NR = Psignal / Pnoise = (Asignal / Anoise)^2 Where P is powe...

circa un anno ago | 0

| accepted

Help with proper parfor

You can't write to a parallel-segmented matrix in the inner loop. Try this: parfor i=1:r col = zeros(n,1); f...

circa 10 anni ago | 0

| accepted

How can I import a .txt file correctly using textscan?

The way to have the most control over a line-based txt file import is to read it one line at a time: while !feof(fid) ...

circa 10 anni ago | 1

Script adapted into a funtion Function not returning equal values

Floating point precision errors. If you need to test for zero, then test for something like: if abs(value) < 1e-5 10^-5 ...

circa 10 anni ago | 0

| accepted

time to number conversion

From memory, if you use |datenum| to just get the time with no date, it doesn't return a number between 0 and 1. But you can ge...

circa 10 anni ago | 0

| accepted

Do you think that MATLAB is expensive?

Yes, I think it is expensive. In New Zealand, it's about $2000 per toolbox. The compiler is over $8000. The work I was doin...

circa 10 anni ago | 0

Can you use cell or struct as function input？

Yes, and yes. I'm puzzled that you're asking this here when you could quite easily test for yourself... Part of the process ...

circa 10 anni ago | 3

| accepted

Save data from a loop

I think this might be what you want: for f = 1:40 for g = 1:40 i = (f-1) * 40 + g; dpTxcouple1(:,:,i) = ...

circa 10 anni ago | 0

Answering my own question

If it really is about something cool, then I'm in agreement with the others. Go for it... People could still add their own ans...

circa 10 anni ago | 0

can someone explain this code?

|x1_Y| is an array of indices. You're doing a boolean test on |x1(10:300)| to determine if a point is an outlier. That is, it ...

oltre 10 anni ago | 0

| accepted

Need some assistance with "if" command

Oh, the better way is to use the proper MATLAB error function: if a < 0 error( 'Not a valid input.' ); end

oltre 10 anni ago | 0

Need some assistance with "if" command

If you don't have a function or anything to return from, there's a sneaky little trick you can use. This can be useful for othe...

oltre 10 anni ago | 0

| accepted

As a Software Engineer, Why should I use MATLAB?

From one developer to another, the answer is: *why not??* What do you have to lose from having another tool (or rather, arsen...

oltre 10 anni ago | 1

What do I have to do to sort strings properly in Listbox?

Don't ask the same question just because nobody answered it yesterday. If you are impatient, write a comment on it to bump it b...

oltre 10 anni ago | 0

| accepted

how to convert Julian date to Gregorian date ?

Use |datestr|

oltre 10 anni ago | 0

| accepted

realtime data streaming between matlab and opencv, visual c++

How "realtime" do you need? If you were polling a file multiple times a second, would that be sufficient? Can you do your anal...

oltre 10 anni ago | 0

fprint error

Like the error message says, some of your inputs are structs, and that's not allowed. Run the following code to check the types...

oltre 10 anni ago | 0

What is the purpose of this line in MATLAB's "factorial.m" function?

I would hazard that it is there to handle the special case of computing zero-factorial, which of course is 1.

oltre 10 anni ago | 0

importing csv array of unknown size, characters

So the general thing is this... Keep track of the current state outside the loop: line_num = 0; % Current CSV line number...

oltre 10 anni ago | 1

Non-numeric matrix to string

It's not a matrix. It's a cell array. You can try converting the whole thing to strings with something like: [M{:}] ...

oltre 10 anni ago | 0

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Computer Vision - Feature Detection and Tracking - Tracking a RC car in a video

Of course, but you might have to implement a bunch of complex algorithms yourself. If you're not familiar with vision processin...

oltre 10 anni ago | 0

Find Min& Max Togather

Well, I do it like this: function [Amin, Amax] = minmax( A ) Amin = min(A); Amax = max(A); end Note: Not to...

oltre 10 anni ago | 0

Slightly off topic: determining at the Windows system level when my process is done

Why don't you invoke the shutdown as the last thing your MatLab script does?

oltre 10 anni ago | 1

Matrix to Table format

Are you saying you want to generate the SQL: CREATE TABLE my_table blah blah blah Followed by INSERT INTO my_table ...

oltre 10 anni ago | 0

Combine Two Different Images With Different Gain Values

Here's what I'd do... Convert all your images to 16-bit. Then take the factor-1 image, multiply it by 10. Then take the fac...

oltre 10 anni ago | 1

| accepted

Temporal processing of image stack

Well, I'm not known for my solutions that take advantage of inbuilt MatLab functions... Maybe something like |filter| would be ...

oltre 10 anni ago | 0

Financial contract value

Just a snippet of coding advice from me... If you need to use a number more than once, especially if it relates to how many v...

oltre 10 anni ago | 0

Entering data into MATLAB from a csv file containing both data and letters

textscan(currentLine, '%s%s%c%d%d%d%d%f%f')

oltre 10 anni ago | 0

Deleting X-Y points that are not near other points on a field of data points

Naive (brute force) implementation given by per isakson looks sufficient for this problem. O(N^2) is okay for 900 rows. For la...

oltre 10 anni ago | 0