Custom MATLAB Functions in Simulink

A custom MATLAB function script can be incorporated into a Simulink diagram with an "Interpretted MATLAB Function" block. This brief tutorial demonstrates a simple example with a couple inputs and outputs.

[@AngeloHafner]

Simple and practical. Thank you for sharing this Knowledge.

[@jbarrena90]

Many thanks for your help!

[@ayyappakurapati7595]

can you help me how to write sin(wt+120) in matlab simulink

[@apm]

It is just like you've written it but you want to use sind for degrees and sin for radians. www.mathworks.com/help/matlab/ref/sind.html Here is more help: apmonitor.com/che436/index.php/Main/ProjectProgramming

[@fs0mid]

thank you very much, it helps me a lot

[@nldhr1990]

great video

[@alicherifabdelkader1399]

Thank you

[@alimoshkriz3574]

Hery guys i wanna to use a data in s-function . how i can i do it ? my data is related in two variable as x,y

[@apm]

Here is an example on importing data either in Simulink (see apmonitor.com/che436/index.php/Main/ProjectProgramming) or else in a MATLAB script (see apmonitor.com/che263/index.php/Main/MatlabDataAnalysis). Let me know if you have any additional questions.

[@maatheking2010]

Dear sir i use matlab 2007 and i need a block to calculate settilling time , max over shot and other control parameters ? can you please help in that

[@apm]

+maatheking2010 You probably want to send the output data to the workspace and then post-process after the Simulink has finished running to determine settling time, max overshoot, etc. Another way is to plot the data and determine those graphically.

[@kagain69]

How is the simulink coder compatibility? can you make C out of it or does it require some more preparation?

[@rrc]

You should be able to make C code out of most Simulink models: www.mathworks.com/help/dsp/ug/generate-code-from-simulink.html The C code that it generates isn't very readable (or fast) but it does allow you to prototype quickly.

[@lion_in_the_den8856]

hi,i have made a electrical simulation in simscape and i need to obtain DWT of a certain phase current but it seems to me that there are some errors.do i need to do some conversion in the phase current?

[@apm]

Unfortunately I'm not familiar with simscape. There may be some answers on Stack Exchange or from the MathWorks website.

[@aldilover1]

Dear Sir, I was wondering if I was using Simulink to simulate an electric circuit that uses a battery, and I wanted to use the SOC (state of charge) of the battery as the input of the function. How should I go about it?

[@apm]

Here is one project that uses batteries and SOC: kzbin.info/www/bejne/hGetmKp4otd3obM You may consider making a loop with the difference between charge and discharge and sending that through an integrator before the loopback. You'll also want to account for the inefficiencies of the charge / discharge rates.

[@mulashedavid1447]

Thanks for the video... Is it possible to use if statement in the matlab script? I have 3 outputs [S(1); S(2);S(3)] and 4 inputs; The output is a calculated from the inputs {x(2); x(3) and x(4)}. The if statement is performed on x(1). Code responding error; output 'S' not assigned. Thanks again

[@apm]

Here is additional help on custom functions: apmonitor.com/che436/index.php/Main/ProjectProgramming You may need to return S from your function.

[@peterbennett5555]

Hi, I have written a matlab .m file which communicates with a touchscreen via an Arduino mega. The code returns a 2 x 1 matrix relating to an x and y coordinate. If I wanted to convert this m file to a Simulink block can I follow your approach as outlined in this video or is there a better way.

[@apm]

+Peter Bennett, you may want to look at a triggered subsystem as well. The trigger could be when the program detects contact with the screen or some other input. An interpreted MATLAB function is good for converting subroutine functions into Simulink but it may not be the best fit for this application.

[@akshayshinde8573]

Hey man, can you please tell me how can u differentiate between the multiple output you produced at the end of the video?

[@rrc]

Akshay Shinde, select a demux as shown at 7:29 to split a stream into multiple signals.

[@Zaidious1]

Great video! Perhaps you can help me. I am trying to create a custom block that will be able to compute z=e^(Ts) - where T is a sampling period and s is of the domain. Not sure how to create a block that will read this as a domain and not as a variable

[@apm]

Your function looks like the z-transform for discrete systems. I recommend a "transport delay" block for implementing a function like e^(-T*s) in the Laplace domain (s). You can also use discrete transfer functions that use z (or q) instead. Look for discrete transfer functions in the Simulink library.

[@naadhami2273]

hey there.. i wanna make a function whch takes multiple input variables and gives multiple outputs..how can i do it?

[@apm]

You can add additional inputs to the place where you have just one. For an output you'll need to return an array of values.

[@naadhami2273]

I need help sir.. i want to find the value of firing angles alpha 1 ,alpha 2 and alpha 3 from the input Xa ,Xb, Xc... i wrote this code in matlab bt it gives so many error..plz help me correct this code sir

[@naadhami2273]

@@apm i wanna talk to u..can i get ur email or something ..this is reallu urgent

[@naadhami2273]

And as i mentioned above.. the firing angles is to found by solving an equation.. so basically what i got to do is, the input to my function is Xa ,Xb,Xc and by solving the a symbolic equation of the form (a^2 +abcXa ==6 )something like this...and value of alpha1,alpha2, and alpha3 is to be found which is the olp of the function

[@naadhami2273]

Help me plz

[@mondayikhide3101]

Nice video. Sir, please any help with simulink block to specify number of samples

[@rrc]

Monday Ikhide you can determine the number of samples reported by using a "to Workspace" block that will make your data available after the simulation. If you need something to happen at particular times, you can use a triggered subsystem. Let me know if that isn't what you are asking.

[@mondayikhide3101]

Many thanks

[@fridahermosisima]

Hello! If you could help me it would be great! (In simpowersystem) I'm trying to insert a resistor that accepts an input signal, but I can't. It seems that it's not compatible with the ones that are already in Matlab I need that this resistor varies in function of the input signal, because it will be connected to the outputs of a solar panel (simulated) and this resistor receives the current signal from the inverter so... jajaja thanks again!!

[@apm]

+Frida GüerecaEstrada, I probably can't help you with simpowersystem because I haven't used it before. However, if you want to simulate a resistor in a circuit then the current should be equal for the input and output. The only thing that will change through the resistor is the output voltage that is based on the current.

[@fridahermosisima]

Thanks!

[@himanshiacharya864]

Hello sir, i want to take input from the users using simulink,Is there any function for scanning input from the usres.

[@apm]

Yes, look in the Sources category in the Simulink library. You'll find a couple different options for inputs. I like to use an input slider because you can specify an upper and lower bound and the user just needs to slide the bar back and forth to change the input.

[@himanshiacharya864]

+APMonitor.com. okiee its really helpful thank you :-)

[@heysoymarvin]

Thank you :)

[@firdousulnazir9334]

Nice

[@FarooqKifayat]

Dear APMonitor.com if i have to simulate a 3 scalar nonlinear differential equations . should i do it by calling the runge kutta from a matlab built in function in simulink or should i use an S function. what will be the advantages of the S function over the matlab built in function block?

[@apm]

+Farooq Kifayatullah You can use either but the MATLAB function will be a lot easier to implement. The advantage of Simulink is that the model inputs and outputs are easier to manually manipulate and possibly to the connect with other models. If you just need to simulate some differential equations then the APMonitor modeling language (freely available) is another option. There are some tutorials here: apmonitor.com/che263/index.php/Main/MatlabDynamicSim

[@mikailhossain4335]

+Farooq Kifayatullah HI , I found a 74% OFF coupon to Learn Matlab Udemy course www.udemy.com/learn-matlab/?couponCode=ML25

[@FarooqKifayat]

thanks mikail i really dont have the money

[@apm]

+Farooq Kifayatullah Sorry for the spam message - I've been getting many of them recently. I reported the message to Udemy.com and they are taking appropriate actions.

[@creactivee_ID]

Thank you for the tutorial :) can you help me to do my project, I would to know how to create sinusoidal single bump with simulink ?

[@apm]

+Erick Chandra you could add two sinusoidal functions together with a "sum" function. One of them should have a transport delay of pi. This way, you'll have a sine function up until pi and then the two will cancel each other after that.

[@sandhyaramasubramanian2375]

Hey Could you help me identify how to access and edit codes of functional blocks already present? ( I mean ones that are coded by Matlab and not custom coded) Say like counter functional block present in Switches and Counters, Simulink (dspswit3).

[@apm]

Sandhya Ram Unfortunately, I don't think it is possible to edit functional blocks that are already present. You can modify several of these functional blocks, however. Right-click the block and select "Properties". You will see a tab "Callbacks" that allows you to program custom functions and scripts with certain events related to the Simulink simulation.

[@sandhyaramasubramanian2375]

APMonitor.com I am grateful for your quick reply. I am unable to edit/select any thing in Callbacks. I want to make a tunable input, maximum count, in Counter (Functional Block in Switches and Counters) as an one of the input parameters along with Inc, Rst, Hit and Cnt. Could you help?

[@apm]

Callbacks allow you to run a custom script when certain events happen. You'll need to program your custom script and then add the call to it in the callback section.

[@sandhyaramasubramanian2375]

Alright. Thank you very much.

[@sandhyaramasubramanian2375]

APMonitor.com, Sorry to bother you again! I used Embedded MATLAB Function to code an Up counter with loadable upper count limit. The custom designed block outputs a "Hit" signal based on the upper limit of the counter. The code is: function Hit = Counter(Clk_rising,Reset,Max) while(Clk_rising) if(Reset) count = 0; elseif (count

[@wijakpornsukvitoon1832]

Dear sir, This's nice video. I would like to know about transferring data from Simulink to M-file, and then send back signal from M-file to Simulink that is real-time, How to do this? I hope you will send the answer soon. Thanks a lot sir.

[@wijakpornsukvitoon1832]

I would like to execute the Simulink and M-file together that I would like to keep data in previous signal and calculate signal in present in Simulink. Thanks sir

[@apm]

+Wijak Pornsukvitoon The m-file will be called by the Simulink model as it executes. You can have many inputs and output to the m-file with blocks such as "MATLAB Function" or "Interpreted MATLAB Function" (my favorites to use for this type of problem). You can also use an S-function if your equations are differentials.

[@wijakpornsukvitoon1832]

+APMonitor.com Thanks sir

[@r4id1337]

Hey really nice video :) I hope you can help me: I want to know the solution for x1 of the following function (i know u1,u2,u3): u1=(u2-x1)/ln((u2-u3)/(x1-u3)) What i have to write ?

[@apm]

+「r4id 」, I'd recommend using fsolve. See the second example for solving nonlinear equations at this page: apmonitor.com/che263/index.php/Main/MatlabSolveEquations You'll only have one equation and one unknown.

[@maatheking2010]

Dear sir i use matlab R2013b if i have function y(t) as following t=[ 1 2 3 4 5 6 7 ] y=[ 2 10 15 20 30 60 70] i want to use y in simulink how i can define this function in simulink thank you in advance------------ where t is the time

[@apm]

+maatheking2010 Please see apmonitor.com/che436/index.php/Main/ProjectProgramming and look at the example problem on "Import Data File into Simulink".

[@maatheking2010]

+APMonitor.com many thanks for your grateful help

[@maatheking2010]

+APMonitor.com dear sir i need to import the function without linearization as in example i have the following function function [ y ] = ahmed( x ) x=[0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60 63 66 69 72 75 78 81 84 87 90 93 96 99 102 ]; z=[9 8.9 8.9 9 8.6 9 9.2 9.3 9.2 9 8.7 8.8 8.5 8.2 7.1 7.1 6.8 7.1 7.7 8.1 7 7.7 8.2 7.2 7.6 7.8 9 9.8 9.9 9.9 9.5 9.2 9 9.4 8.5 ]; y=(05*0.5*1000)*z.^3 plot (x,y) end and i need to import its output as it is to simulink

[@maatheking2010]

+maatheking2010 where x is the time

[@apm]

+maatheking2010 Yes, the files that I posted to the web-site should work for you. You'll just need to modify the variable "time" to be "x". apmonitor.com/che436/uploads/Main/interpreted_Simulink_MATLAB.zip

[@masnsenyuva9182]

hi! great video tutorial ! I have some trouble with an aplication, enunciated bellow : build a model that simulates a first order system of Error ! Referral source not found. in response to an input u = sin(t) using MATLAB Fcn block of User's defined Functions category. excuse my english :p thnx in advance

[@apm]

+Masnsen Yuva Here is another video that describes first order systems: kzbin.info/www/bejne/eHLMn3hjnd5qpZI This video shows how to implement a User defined Function. You can test your implementation by using a built-in "sin(t)" source block and a "Transfer Fcn" block as a first-order system. I hope this helps.

[@masnsenyuva9182]

+APMonitor.com than you! it's very helpful, finally there was an error in the announcement of the exercise! the function which needed to be simulated using the UDF block was 3/s+2!! I just need to know when we use the clock block in simulink ?

[@apm]

+Masnsen Yuva You asked about clock inputs as well - here is some help from Simulink: The Clock block outputs the current simulation time at each simulation step. This block is useful for other blocks that need the simulation time. When you need the current time within a discrete system, use the Digital Clock block.

[@masnsenyuva9182]

exactly as I expected ! thnx a lot :)

[@ati2046]

can i run my face detection .m file in simulink using interpreted function [e-mail]

[@apm]

Yes, you should be able to do this. I recommend that you use a Triggered Subsystem to control how frequently the face detection runs. To slow down the Simulink to match simulation time and real-time, I recommend the real-time pacer: www.mathworks.com/matlabcentral/fileexchange/29107-real-time-pacer-for-simulink