Outputs of a function

Hello! I'm currently writing functions that take input, and need to return a ouput to be used by a later function. However, in the function programming, I know that I have many different variables that I'm defining in order to do the function that I need. So when I try to get the function to do an output argument (i.e. X = function(input);), it gives me the error that I have too many output arguments.

Is there a way that I can label (inside the function itself) the one ouput I want so that it only sees that variable as the correct output?

Answer 1

[tlawren]

Is your function declaration correct? For example, the following two functions are declared to return one and two variables respectively. Both take in three inputs.

 function x = test1(a,b,c)
 function [x,y] = test2(a,b,c)

If your function declaration looks like this

 function test1(a,b,c)

and you try to get outputs from it with

 x = test1(in1, in2, in3)

in your other code, then you will get a "Too many output arguments" error.

See the following for more details. http://www.mathworks.com/help/techdoc/ref/function.html

Answer 2

[Jaden]

Yeah, I don't think that I have the function declared right. However, the problem is that there are way too many "ouputs" in my program that I don't want used as outputs, but are simply used as parts of the transformations.

I'll paste some example code:

this is how I call the function:

function [dataValues] = transformingdata(fileName);

and this the function itself, where you can see that there are a lot of variables going on:

function transformingdata(laser)

%This function takes any polar laser data set and simply transforms it into Cartesian.

%% Determining height and width of transformed scan

[height, width] = size(laser);

%% Determine angles for xvalues

% Laser Radian Step Size == .00436

if(width == 720) xvalues = [95:-0.263541667:-94.75]; % FOR 190 DEGREES end

if(width == 1081) xvalues = [135:-0.2498169664173166:-135]; % FOR 270 DEGREES end

%% Transform degrees into radians

xvalues = ((xvalues*pi)/180);

%% Initialize values

numberOfScans = 1; dataPlot = []; plot2 = []; X = []; Y = []; plotY = []; plotX = [];

%% Transformation loop

    while (numberOfScans < height)

        [X, Y] = pol2cart(xvalues,laser(numberOfScans, :));

        if (numberOfScans == 1)
            Y = Y;
            X = X;
        end

        if(numberOfScans > 1)
        plotY = [plotY; Y];
        plotX = [plotX; X];
        end

        plot2 = [];
        plot2(:,:,1) = [plotY];
        plot2(:,:,2) = [plotX];

        numberOfScans = numberOfScans + 2;
    end

    %%New size

    [he, wi] = size(plot2(:,:,1));

    %%Initialize variables

    numberOfScan = 1;
    plot2(:,:,3) = zeros(he,wi);

    %%Creating translation matricies
    TX = [.09];
    TY = [.25];
    TZ = [-.22];
    TX = TX*ones(1,wi);
    TY = TY*ones(1,wi);
    TZ = TZ*ones(1,wi);

    %%Center of robot loop

 while (numberOfScan < he) 
     dataPlot(numberOfScan,:,1) = plot2(numberOfScan,:,1) + TX;
     dataPlot(numberOfScan,:,2) = plot2(numberOfScan,:,2) + TY;
     dataPlot(numberOfScan,:,3) = plot2(numberOfScan,:,3) + TZ;
     numberOfScan = numberOfScan + 1;
 end

 dataValues = dataPlot;

robot = 'done_data!'

end

[Walter Roberson]

Any variable whose name does not appear on the left side of the "function" statement (and which is not a global or nested variable) will be deleted when the function exit, so it is not a problem to create as many variables as you need to calculate the values that you want to return.