How to resolve this error?

function f = Deflection_Function(x) % NAME THE FUNCTION
Beam_Length = 700; %lENGTH OF BEAM IN CM
Youngs = 50000; %YOUNG'S MODULUS IN kN/cm^2
MoI = 30000; % AREA MOMENT OF INERTIA IN cm^4
Dist_Load = 50; % DISTRIBUTED LOAD IN kN/cm
f = Dist_Load/(120.*Youngs.*MoI.*Beam_Length).*(-x.^5 + 2.*Beam_Length...
    .^2.*x.^3 - Beam_Length.^4.*x); % INPUT THE DEFLECTION
% EQUATION AND ACCOUNT FOR A TARGET VALUE OF DEFLECTION
end
function f = Deflection_Function_with_Target(x,~) % NAME THE FUNCTION
Beam_Length = 700; %lENGTH OF BEAM IN CM
Youngs = 50000; %YOUNG'S MODULUS IN kN/cm^2
MoI = 30000; % AREA MOMENT OF INERTIA IN cm^4
Dist_Load = 50; % DISTRIBUTED LOAD IN kN/cm
f = Dist_Load/(120.*Youngs.*MoI.*Beam_Length).*(-x.^5 + 2.*Beam_Length...
    .^2.*x.^3 - Beam_Length.^4.*x); % INPUT THE DEFLECTION
% EQUATION AND ACCOUNT FOR A TARGET VALUE OF DEFLECTION
end

Error using fzero>localFirstFcnEval

FZERO cannot continue because user-supplied function_handle ==>

@(fzero_start)Defelection_Function_with_Target(fzero_start<target) failed with the error below.

Undefined function 'Defelection_Function_with_Target' for input arguments of type 'logical'.

Error in fzero (line 305)

fx = localFirstFcnEval(FunFcn,FunFcnIn,x,varargin{:});

Error in How_To_Code_Bisection_Method_020123 (line 84)

fzero_root = fzero(fzero_fun,fzero_start);

[John]

It looks like you didn't include all your code--the problem likely stems from how you're calling the function Deflection_Function_with_Target, look inside your How_To_Code_Bisection_Method_020123 function. If you need help with this (it looks like a class project), post that code and walk us through the problem you're seeing and what you've tried so far. We'd love to help!

[Les Beckham]

Looks to me like Defelection_Function_with_Target is being called like this

@(fzero_start)Defelection_Function_with_Target(fzero_start<target)

and the "<" should be a comma ","

Answer 1

[Walter Roberson]

@(fzero_start)Defelection_Function_with_Target(fzero_start<target)

You are asking fzero to invoke a function Defelection_Function_with_Target and pass in to the function the logical result of comparing the scalar fzero_start to target .

The first problem is that it does not work because you do not define

Defelection_Function_with_Target
   ^

and instead define

Deflection_Function_with_Target

but if you fix that typing mistake then function Deflection_Function_with_Target is going to receive scalar true or false as its only input, and would calculate

f = Dist_Load/(120.*Youngs.*MoI.*Beam_Length).*(-x.^5 + 2.*Beam_Length...
    .^2.*x.^3 - Beam_Length.^4.*x)

based on x being either 0 (false) or 1 (true).

There are only two possible outcomes from that, so it is not possible to estimated a gradient from it, so fzero will not be able to find a zero unless it just happens to pass in a value that returns false on the logical test.