[SOUND] So now let's discuss how you can read in and write out results in MATLAB. So, what you're really asking when, you know, when two curves cross, in the case of real data, is where do they come closest to one another?

Data files may be imported into Matlab variables by right-clicking on them in the directory listing. Matlab has a built-in text editor, launchable from an icon on the left end of the Matlab toolbar, or by clicking on an existing file in the Matlab directory window. If index tells you the 16th value of y is the largest, you need to type x parenthesis, index, end parenthesis to display the course finding value of x. Course 4 of 6 in the Systems Biology and Biotechnology Specialization. Run the file by typing the name, or "run name", or run( 'name' ), or right-clicking, or from the Matlab editor. All the way up to five. And, four is greater than two, so the fourth element here, is you get four because that's the forth element.

That's going to give us this result. So, this is a way to compute, when does our, my, subtracted. Or later if you wanted to read this in mat lab, you could type dlm read at the MATLAB prompt.

In some ways this is going to be a continuation of the previous lecture, where we discussed strategies for using MATLAB for data manipulation and analysis. Well, what find does is, it returns the indices of all the elements of your, of your array, where a certain condition is true. We're going to talk about how you can use that functionality of MATLAB. use an escape character (usually \). And then furthermore, remember, this index here is just telling you what number of, what point number in y one or y two is, are these two going to be the closest? If you said little a equals apostrophe I love matlab, apostrophe, then little a in this case is not going to be equal to a number. If you try disp((sprintf("Jane's weight")), You may receive emails, depending on your. Exponentiation, e.g. ). This is a very, powerful programming logic tool. The commands generated are displayed in the command window - Use help or doc to learn more about them, and copy them into scripts as necessary. disp [ 'X = ', num2str( x ) ]; % Print an array of two strings as a sentence. Or, am I checking? Then you can say something like big A is little a comma, square root of A. the same number of both rows and columns. They should be either positive, or they should be equal to zero. So the second element, the fourth element, and the fifth element of A are all greater than two, so this is what the Find command does, is it returns all the indices where a certain condition holds. The course should also be valuable as an introductory overview for students planning to conduct original research in modeling biological systems. But you want to come back to it later, you want, you wanted to sort of stop for a while and then come back exactly where you left off. We're also going to discuss strategies for using if statements and then we're going to talk about exporting and importing results in MATLAB. And so you can look, and you can say okay, the value one is not greater than two, therefore we don't have the one here, this is the first element. And what this is doing is computing the standard deviation of all the values in a. And you can see what the numbers are. I have a 3-by-1 cell that I have imported from excel and for some reason the three entries in the cell have apostrophe's on them: A = ['0.00092779';'0.00097348';'0.00094242']. If you're saying EXP of X, what you're telling MATLAB to do is compute the number E raised to the X power. We'll get to that a little bit later, but what I mean by that is sometimes you don't care about the maximum value itself, sometimes you care where in your array does the maximum value occur. Do not use a word processor or other program unless you are careful to save the file as plain text. Index in this case tells you which element, for instance the sixteenth value of Y is the index where the maximum occurs.

Based on There's also a function called imwrite for image write. We've also used a colon in order to access all the elements along one dimension, right. Apostrophes can be used to transpose a matrix. Lectures provide biological background and describe the development of both classical mathematical models and more recent representations of biological processes. Let's assume that we had a one D array called little a. And here's an example of how you could compute that using MATLAB. But, for some of you I know that MATLAB is the first programming language you're encountering. And, note, there's, if you wanted to compute this particular ten by four array, there's different ways to do it.

I'm using SIMULINK, in the mask of the block I have created a button that opens a dialog box searches for file using 'uigetfile' in return I get [filename] which is character.

Semicolon can be used at the end of the line to suppress output. And then what we want to say is, if a sub i is less than zero, then we use this command called disp. Any command that can be typed in the command window can also be run from a script file, which is just an ordinary text file containing Matlab commands. See also basic matrix operations, May be different for scalars versus arrays versus combinations of both. In this lecture, we're going to discuss several useful MATLAB built-in functions, such as those you can use to compute the mean, the maximum or the standard deviation of data that you may have. ( i.e. Still learning all the tips and tricks! Can you clarify what you want & where you want it? If that value of A sub I is equal to zero or it's greater than zero, it's just going to skip over this and nothing is going to happen in this case. The first week on MATLAB was a great refresher since I hadn't used MATLAB in a few years, Easy to follow up and clear lectures to understand dynamical modeling methods. * and ./ require that the matrices have the same sizes, i.e. But we're going to have a different focus compared to that last lecture. one, five, two, four, three. And what this is telling that letter to do, DLM rate, in this case, stands for the limited, right. Save with a ".m" extension - Automatic when using Matlab's editor. Secondly, what variable to put into that file, which in this case, the variable we want to put in that file is capital A, and then this third thing is telling them to separate the values by backslash t. What's useful about this is now your, your file A.dat, you can read that into Microsoft Word. Elementwise - . Disp in this case is short for display. In this case you said, x at peak equals number to string index. It can't be read by other, by other programs, but it is very useful in the sense that it will just save all the variables that you had, everything that you had done up to that point. Or you could say little g equals EXP of A. And here's a practical example of how you could use this. These techniques are based on biological mechanisms, and simulations with these models generate predictions that can subsequently be tested experimentally. it must be possible to multiply the matrix by itself. Based on Reload the page to see its updated state. 2022 Coursera Inc. All rights reserved.

We've talked about how semicolons, colons, periods, and apostrophes can have special, special meaning in MATLAB. So what we want to do is we want to go through our one-D array a, and every time we see a negative value, we want to alert the, the user, so you know about it. So that's going to take the numbers one through 10 in a row vector and apostrophe is going to transpose it, so it's going to convert that into a column. Other MathWorks country We've used the colon to create batches of equally spaced numbers, right?

We can compute little b equals the mean of a. . https://www.mathworks.com/matlabcentral/answers/34770-how-can-i-use-apostrophe-as-a-text-in-legend#comment_513543, https://www.mathworks.com/matlabcentral/answers/34770-how-can-i-use-apostrophe-as-a-text-in-legend#answer_43655. That's going to create a file in whatever directory you're in that's called mat, it's going to have the name matlabsession, with the, extension .mat. So you want the minimum but you want the minimum to be absolute value. offers. So maybe what you care about is not whether you have a particular value in your array that is greater than a particular number but which indices in your array are greater than that. In this case is roughly 0.37. area = pi * radius^2. So, several useful MATLAB built-in functions can be summarized as follows. Knew it would be something simple. And then you had y two which is the red curve which decreases to the function of x. Now if we said little f equals the square root of A, in this case we're not going to get a single number like we did with these other functions, we're going to get another one by five array, with these five numbers here. ( ellipses ) - Placed at the end of a line accessing elements of a matrix. An ( M x C ) matrix * a ( R x N ) matrix yields a ( M x N ) result, where R must equal C. To divide two matrices requires that the have the same number of columns. Well, in that case, you have to use a double equals sign because you need to specify to MATLAB. And then we also discuss how MATLAB includes several convenient methods for writing out results and reading in results. You can combine these functions with concatenation, like we talked about before. So the first element times the first element, the second element times the second element. Five is the maximum value in this column.

Semicolons we've also seen used for vertical concatenation, right? To multiply two matrices requires that the number of columns in the first matrix match the number of rows in the second. We computed a dot carat two, this is saying take a to the second power, but not exactly. So you can probably see what how the if statement is useful in this case. Format specifiers are used repeatedly until all data values are printed. This might be a good time to pause as you think about it. Unable to complete the action because of changes made to the page. https://www.mathworks.com/matlabcentral/answers/508131-how-to-remove-the-apostrophe-s-from-a-cell#answer_417779, https://www.mathworks.com/matlabcentral/answers/508131-how-to-remove-the-apostrophe-s-from-a-cell#comment_803509. When we computed A squared, you noticed that we put a dot here, right? So if we typed in little a equals 1:10, put parenthesis around that and put an apostrophe. So, you could have your blue, which would be, you know, these dots here and your red would be these dots here. It's going to be equal to this text, I love matlab. They could be off by 0.01 or they could be off by 0.01 or 10 to the minus seven. Unable to complete the action because of changes made to the page. However from your Answer, i also figured this one out. So the three things that we're telling dlmwrite in this case are, first of all, the file name, A.dat. This is a very useful command for determining not whether something is true, but, not whether something is true but where something is true. So, that's why we said we computed an index in this first line and then we computed x sub index in the second line to tell us what the crossing point was. We are now onto the third part of our lecture on how to use the MATLAB programming environment to form scientific computations.

You can also select a web site from the following list: Select the China site (in Chinese or English) for best site performance. And in the case where you want to check to see whether or not something is true you use a double equals sign. Reload the page to see its updated state. ( apostrophe ) - Used to quote strings of text. Ordinarily every Matlab command generates a result, and that result is displayed in the command window. When applied to a matrix, the matrix must be square. You had y one, which is the curve here which increases to the function of x. So it finds all the elements in a that have a value greater than two. Now of course mathematically the curves cross where y one equals y two. So that's when this number is, when this difference y one minus y two is going to be closest to zero. So just like you have a file called dlmwrite which is a way of exporting tab delimited text files dlmread is a way of importing a tab delimited text file or a comma delimited text file. Left division is only relevant to matrix operations: Requires that the number of columns in the numerator and denominator match. What this is doing is computing. your location, we recommend that you select: . So this is just like four loops that we talked about previously. And a second note here is, we've encountered a couple of conditional statements like this. Like we discussed before, this four loop is going to start with a value of one, and it's going to come up to the value of length of a. We don't want to set all of our values of a equal to zero, right?

You could say little a is equal to max of the square root of exp of a, and we get a value like that, of 12.1825. So if you type these four lines in, you'll get the same definition of little a and the same definition of capital A that we got before. And the reason is because max underscore y does correctly hold the maximum value but x(index) is the correct location with respect to x. Because K is the largest value, in this three by three array. ; ( semicolon ) - Suppresses output. So, what we care about in this case is the index, not the actual minimum value itself. Find the treasures in MATLAB Central and discover how the community can help you! And then because this is in a for loop you need to have a second end command here which signifies the end of the for loop. You may receive emails, depending on your. So this one, this is the way of returning the overall maximum of your array. Right-click on one or more data items and select a plot type from the pull-down menu. A squared, comma, sin A, and you would get this ten by four array here, where the first column is A, the second column is the square root of A, third column is A squared, fourth column is the sin of A. The course will be useful for students who plan to use experimental techniques as their approach in the laboratory and employ computational modeling as a tool to draw deeper understanding of experiments. Am I just making an assignment, am I saying a sub i is equal to zero so take the value zero and assign it to this variable a sub i.

for matrix subscripts ), , ( comma ) - Separates arguments in a function or values in a matrix, : ( colon ) - Generally used to indicate a range of values, e.g. We don't really care exactly about the numbers.

So we could have typed in something like this, if a sub i equals equals zero then what you want to display is is zero value found in a particular index. Let's review why that's the case. So, this if command will only execute these two, if, if, statement is set up so that it will only execute these two commands. So, this is going to create what's known as a tab-delimited text file. But you don't want to to spit it back out every single time.

And we wish to determine the values of y and x wherever y reaches its peak. And then we have an end command, here, this end is going to signify the end of the if statement.

And if you're saying to yourself there's an easier way to do this then, yes, you're right, there's an easier way to do this. If I said, if we said little a is big A, three, comma, colon, this will give us the third row of A and all the columns of big A. Is a function of x on the x axis. MathWorks is the leading developer of mathematical computing software for engineers and scientists. And then we've also seen apostrophes used to delineate string variables. In this case, the way the MATLAB interprets the max command, this isn't exactly true. Other MathWorks country

So, these commands would, would do what we need, in this case. Well, you could just say little L is equal to the maximum of the maximum of A. Five is greater than two, so therefore we get a two. An introduction to dynamical modeling techniques used in contemporary Systems Biology research. And these are five choices you have, either yes it gives the correct result which is choice a. And then you can say the crossing point in this case is equal to x sub index. I.e. Seven is the maximum value in this column. Porting plots to other documents, e.g. You can also select a web site from the following list: Select the China site (in Chinese or English) for best site performance. They can read in standard formats like JPEG and TIFF, PNG files et cetera. What if you wanted to find out where our curves cross? Hello everyone. So what this is going to do is print out on our screen. Now what if you wanted to save it in a different format? We've seen examples of that. Based on And you can of course combine functions like this. If it was positive, like it was supposed to be, we don't want to do anything. So a couple of notes on this. In this case, max underscore Y will hold the maximum. Other MathWorks country You may receive emails, depending on your. And in that case, of, you're going to get of course, the number seven. This is a standard programming logic tool. So, to summarize this lecture, we've learned that if statements, just like for loops, are very powerful computing tools. There's a little twist here. This course focuses on dynamical modeling techniques used in Systems Biology research. So now let's talk about something that's called the if statement. MathWorks is the leading developer of mathematical computing software for engineers and scientists. The numerator should have at least as many rows. Then we can type this, dlmwrite parenthesis, apostrophe A dot dat end apostrophe, comma A, comma, and then, apostrophe, backslash T, apostrophe, then end parenthesis. We could say for i equals one, up to the length of a. So, index, in this case, just equals 16, because you can count up here, and you can see when you get to the 16th one, that's where you're at a maximum. Now if you say display peak Y equals number to string max underscore Y, this line is fine. And all the values in this one-D array should, in principle, be positive, or at least they, they should be non-negative. jpeg. Modulus is the function "mod", not an operator. These five numbers. Am I, am I making an assignment or am I like checking to see whether or not something is true. So let's go through an example for how we could, how we might use an if statement. So what MAX does, is it computes the maximum on a column by column basis. The following commands are generally useful, particularly when first learning Matlab, i, j - square root of -1, UNLESS they have been re-defined, inf( N ) creates an N x N array of infinity, inf( M, N ) creates an M x N array of infinity, % ( percent ) - Indicates the start of a comment, which extends to the end of the line.

So, in this case, the condition you're asking is, where is a greater than two? The period is used to perform array computations versus matrix computations. Find the treasures in MATLAB Central and discover how the community can help you! So this is computing with MATLAB, part three. my format is like that'Date' 'Time''07.12.2009' '08:18:58''07.12.2009' '08:18:59''07.12.2009' '08:19:00''07.12.2009' '08:19:01''07.12.2009' '08:19:02', i want it in this formatDate Time07.12.2009 08:18:5807.12.2009 08:18:5907.12.2009 08:19:0007.12.2009 08:19:0107.12.2009 08:19:02. So you could write a.dat then you could read it in later using this command called dlmread. You know, hey, that we have a negative number here where we're not supposed to be a negative number, and then what we also want to do is we want to set the value equal to zero. So, let's review why we did it, this way. And then this, number three is also greater than two, and three in this case, it's the fifth element. This is just meant to illustrate how the if statement works. So, now let's review what we've learned about MATLAB syntax. The course is appropriate for advanced undergraduates and beginning graduate students. The value five, which is our second element, which has an index of two. And also standard software packages that are used for things like plotting can read these, these tab limited text files. So we showed a lot of examples where you type in some variable name is equal to some output and MATLAB will spit that back out. We will get D equals five, and then, we will get index equals two. That computes, mean computes the average.

So this is a, this creates a type of file, a .mat file, it can only be read by MATLAB. Real data are defined in individual, data points. ( Files must be plain text only. Remember, this is a way that you can access the entire first column of A, the entire second column of A, the entire third column of A. So it's going to go through all the elements of a. Or we could say, little d equals the max of a, that's going to give us the maximum value in this one by five array, which in this case is, of course, going to be equal to five. Commands can either be typed into the file directly, or dragged from either the command or history windows. One is that there are easier ways to test these sorts of things. Well the maximum occurs here, which and, in this case, five is the second element of our array a. With something like this, these, this set of nine numbers arranged three by three. to include in a written report: From plot window, select "File, Save As", and select a file type compatible with your other program, e.g. What have we used the colon for?

5:10.

I want to insert apostrophe in legend for example, "Jane's weight" but MATLAB handles ' as a command. So the reason this is two is because you can see where does the maximum occur. your location, we recommend that you select: . Negative value is found at index six, or index 14, or index 21, or whatever. K in this case, is going to be a one by three array, three, five, seven. There's mainly only two schools in how you introduce delimiter characters in strings: double the delimiter. For example, array.^2 would square each element of the array, as opposed to multiplying the array by itself. Advance your career with graduate-level learning, Lecture 4 - Computing with MATLAB - Part 3, Lecture 5 - Computing with MATLAB - Part 4. And to display that, you have to take x parenthesis index end parenthesis. This is where, this is the point that it would it would identify, is where the two curves cross one another. What if you really wanted to get seven out of this. Find the treasures in MATLAB Central and discover how the community can help you! A scalar can be added to or subrracted from an array, in either order. Now what if A, instead of using little A as a one by five, array or a vector, what if we had capital A and we had this as a three by three array. And then what we want, the other thing we want to do is, every time that a sub i is less than zero is, we want to set a sub i equal to zero. A sort of related command here is if we say j equals find a greater than two. But what if you didn't want to do this on a column by column basis?

If you say capital B equals capital A apostrophe, you can take this tall and skinny matrix and convert it into a short and fat matrix. This is the way used by matlab, VB, and ? j is two, four, five. It will only display this message and it will only set the value of A equal to zero if that corresponding value of A sub I is less than zero to start with. sites are not optimized for visits from your location. The only time we want to set the value of a equal to zero, is if that particular value of a was was negative to begin with. Choose a web site to get translated content where available and see local events and The default would be to separate them by commas, but sometimes separating them by tabs is, makes them a little bit easier to read. I would like to plot the values of these on a graph but I cannot as I get a Line Class property error due to the apostrophe's. width.precision - E.g. This is used by pretty much all the other languages, C languages, Java, Python, PHP, etc. So, if you want to check whether something is equal to zero, you have to use a double equal sign. When selecting multiple data items, the order of selection is important. Is, is one value of a exactly equal to zero? The answer in this case is D. No in this case the lines of code do not give you the correct result.

As we've discussed, saying big C equals A times B is different from saying big C is A dot times B. And if you don't want it to spit it out, you put a semicolon at the end of the line and that will tell MATLAB. So this is a way that you can easily combine functions by embedding one within the other. Remember from previous lectures that apostrophe means transpose. You could say, little A equals 1:10 with () around it, and then an ; to indication transpose. https://au.mathworks.com/matlabcentral/answers/291622-how-o-add-apostrophe-in-a-char-or-string-array#answer_226324, https://au.mathworks.com/matlabcentral/answers/291622-how-o-add-apostrophe-in-a-char-or-string-array#comment_374439, https://au.mathworks.com/matlabcentral/answers/291622-how-o-add-apostrophe-in-a-char-or-string-array#comment_374440. sites are not optimized for visits from your location. And for all the numbers one through five, the mean value in this case is going to be three. Well, the simplest thing to do is just to type save matlabsession. One, four, two, semicolon eight, zero, three, in this case, will create a two by three array. So that my code can pick 'filename' as string value. Maybe you're, you're laptop was running out of batteries. So all you would have to do is say well, let me compute y one minus y two and find where that's equal to zero. Max y index equal max of y and then display peak y equals, number to string, max underscore y and then display x at peak equals number to string index. The question now is, does this give you the correct result, and if not, why not? So that's why you get one, one squared is one, two squared is four, down here, seven squared is 49, etc. You can also select a web site from the following list: Select the China site (in Chinese or English) for best site performance. That will give us this number, c equals 1.58. What you care about is what's the value of x at this point, where the two curves come closest to one another. The approaches taught here can be grouped into the following categories: 1) ordinary differential equation-based models, 2) partial differential equation-based models, and 3) stochastic models. And then, a third way that you can, ex, re, import and export data in MATLAB is through images there's a file called imread for image read, sorry there's a function called imread for image read. This is common to just about any programming language you will encounter. But what if the values are never exactly equal, right? I mean, this is true in a formal mathematical sense but when you're looking at real data, like, real data are not defined continuously. And you can see that they never exactly overlap. Is there a way to remove these? If you said little a is zero, colon zero point zero one, colon five, it will start at zero, to zero point zero one, go to zero point zero two, etc. When does my difference vector y one minus my, y two get closest to zero? The dot times in this case says perform this multiplication on an element-by-element basis. You could do it like this. Don't tell me the answer after we make this assignment. %5.2f prints a floating point number in a space of width 5, with two digits right of the decimal point. So now let's assume you type the following lines in your command window. What you care about is what's the value of x at that number. Probably the most useful commands are what are called save and load in this case. Reload the page to see its updated state. And then when you type, when you load that back in you can just start wherever you left off. Choose a web site to get translated content where available and see local events and We don't care in fact how close these two curves come to one another, right? The reason we made this a dummymin is because this is a value we don't really care about. Or you could say, little e is equal to the sum of a. sites are not optimized for visits from your location. These testable predictions frequently provide novel insight into biological processes. And the second variable you give it, index, is what's holding the location of the maximum in the array. You see, three is the maximum value in this column.

We encountered this, function called find. [NOISE] We'll conclude this lecture with a self assessment question to see how you understood the concepts that we just discussed. What if you wanted to save it in a format that could be read by, by other programs? So, if we read, if we typed something called sample script two and that created an A and lets just say for the sake of argument sample script two creates an array capital A with size 100 by 10. And that's where find can be very useful. And then you can plot x sub index versus y one sub index in green, and this point here would appear. Or there's four possibilities for why these particular lines of code do not give you the correct result. MathWorks is the leading developer of mathematical computing software for engineers and scientists. And then we see an apostrophe used for a couple of times. Scalars can be multiplied by or divided by arrays in either order. The reason we know that it's a tab-delimited text file is because of this little thing here, this backslash t. This says, take all your variables in A and separate them by, by tabs. That's going to sum all the values one through five, which is going to give you a value of 15.