Write the function call_myfn, which calls myfcn.

function [x, y] = call_myfcn(n)
%#codegen
x = myfcn(n, 'mode1');
y = myfcn(n, 'mode2');
end

function y = myfcn(n,mode)
coder.inline('never');
if strcmp(mode,'mode1')
    y = n;
else
    y = -n;
end
end

Generate standalone C code. For example, generate a static library. Enable the code generation report.

codegen -config:lib call_myfcn -args {1} -report

In the code generation report, you see two function specializations for call_myfcn.

The code generator creates call_myfcn>myfcn>1 for mode with a value of 'mode1'. It creates call_myfcn>myfcn>2 for mode with a value of 'mode2'.

In the generated C code, you see the specializations my_fcn and b_my_fcn.

static double b_myfcn(double n)
{
  return -n;
}

static double myfcn(double n)
{
  return n;
}

To prevent the function specializations, instruct the code generator to ignore that values of the mode argument are constant.

function [x, y] = call_myfcn(n)
%#codegen
x = myfcn(n, coder.ignoreConst('mode1'));
y = myfcn(n, coder.ignoreConst('mode2'));
end

function y = myfcn(n,mode)
coder.inline('never');
if strcmp(mode,'mode1')
    y = n;
else
    y = -n;
end
end

Generate the C code.

codegen -config:lib call_myfcn -args {1} -report

In the code generation report, you do not see multiple function specializations.

In the generated C code, you see one function for my_fcn.