Function Handles

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• Misc
  • CIT looking for database programmer, web assistant interns
    • Paul Jackson (jackson@geneseo.edu) for more info
• Questions?
• Function Handles
  • Sections 10.1 and 10.2
    • Anonymous function
      • 1-line, not in M file
      • Syntax: fnhandle = @(args) body
        • e.g., @(radius) pi * radius .^ 2
      • Calling with no arguments needs parentheses
    • Function handles can be used to build functions
      • Handle to built-in function: newname = @functionname
      • Function functions take functions as arguments via handles
        • eg., fplot, feval, fzero
  • Examples
    • Write a function that takes another function as an argument and calls it
      • f′(x) = lim_h→0 ( f(x+h) - f(x) ) / h
      • Or lim_h→0 ( f(x+h) - f(x-h) ) / 2h
        

        function [ d ] = deriv( f, x )
        %DERIV Estimate derivative of F at X
            h = 1e-10;
            d = ( f(x+h) - f(x-h) ) / ( 2*h);
        end

      • Examples of calling that function
        

        >> deriv( @(x) 2*x, 0 )
        ans =
            2
        >> deriv( @(x) x.^2 + x, 2 )
        ans =
            5.0000
        >> deriv( @tan, 0 )
        ans =
            1
        >> deriv( @resultdemo, 1 )
        ans =
            2.0000

• Integration Lab
• Next
  • Finish integration lab

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