why did i receive these errors during developing a simple code in Mat-lab function block?

function [y1, y2, y3, y4, y5]= abs(u1)
%#codegen
if u1 < 48.2
  y1 = 1

     if u1 < 48.2
        y3 =0

      elseif u1 < 48.2
            y4 =0

      elseif u1 < 48.2
                y5 =0
     else
        return
     end
  elseif  u1 >= 51.8
      y2 =1  
  else
      return
  end
  end

% #received errors are:

1. Output argument 'y1' is not assigned on some execution paths.
Function 'MATLAB Function1' (#24.31.34), line 1, column 32:
"abs"
Launch diagnostic report.
2. Errors occurred during parsing of MATLAB function 'MATLAB Function1'(#23) 
3. Code Directory :
     "D:\myproj\slprj\_sfprj\rehearsal\_self\sfun\src"
Machine (#22): "rehearsal"  Target : "sfun"

[Stephen23]

Never call your function abs, because this is the name of the extremely commonly used inbuilt abs function. For the same reason you should never use the names length, size, i, j, cell, etc. etc.

Answer 1

[Walter Roberson]

Unless u1 < 48.2 you do not assign any value to y1.

In MATLAB, you do not always have to assign to all possible outputs, but if you do assign to an output you should always have assigned to all outputs to the "left" of it in the list of outputs.

You appear to be using Simulink. You should probably be assigning to all possible outputs anyhow.

[ahmed al-kady]

yes, i am using simulink and all outputs are assigned to certain blocks however this error appear.