nonlin_secant


nonlin_secant, a MATLAB code which interactively applies the secant method to seek a root of f(x) using two starting values a and b.

The user enters a formula for f(x), and the values of a and b.

The program then repeatedly applies the secant method until it encounters a very small function value, or a very small change of sign interval, or it detects a problem with the iteration.

The program can be invoked by a function call, in which case the string specifying f(x) must be quoted:

        [ a, b, fa, fb, it ] = nonlin_secant ( 'x^2', -1, 3 )
      
or, if called with no arguments, it will request them:
        [ a, b, fa, fb, it ] = nonlin_secant ( );
        Enter function formula, like x^2: x^2
        Enter first point, a: -1
        Enter second point, b: 3
      

The function is specified as a string which is either:

The string should not contain any spaces between symbols, except when it is passed as a function argument in quotes.

It is not necessary to use the "dot" notation for expressions involving '*', '/', or '^', but it doesn't hurt either.

Examples of function specifications:

        x^2
        x.^2
        3/(x^4+5*x-6)
        sin(7*x)*sqrt(x)/8
        wiggle(x)     <-- where "wiggle.m" is a user-provided M file.
      

Licensing:

The computer code and data files made available on this web page are distributed under the MIT license

Languages:

nonlin_secant is available in a MATLAB version.

Related Data and Programs:

nonlin_secant_test

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Source Code:


Last revised on 21 June 2019.