Matlab Functions

One of the most powerful ways to use MATLAB is through breaking up the code into smaller execution units that does only a specific task.  These are called functions.  They are also refferred to subroutines in other languages.  In VB these correspond to Function and Sub procedures.

In Matlab there are built-in functions and the ones you create.

Matlab built-in functions

There are three types of built-in functions types available in MATLAB

    Elementary built-in functions

    Typing     help elfun at the prompt will give you a list of these functions

Elementary math functions.
 
  Trigonometric.
    sin         - Sine.
    sinh        - Hyperbolic sine.
    asin        - Inverse sine.
    asinh       - Inverse hyperbolic sine.
    cos         - Cosine.
    cosh        - Hyperbolic cosine.
    acos        - Inverse cosine.
    acosh       - Inverse hyperbolic cosine.
    tan         - Tangent.
    tanh        - Hyperbolic tangent.
    atan        - Inverse tangent.
    atan2       - Four quadrant inverse tangent.
    atanh       - Inverse hyperbolic tangent.
    sec         - Secant.
    sech        - Hyperbolic secant.
    asec        - Inverse secant.
    asech       - Inverse hyperbolic secant.
    csc         - Cosecant.
    csch        - Hyperbolic cosecant.
    acsc        - Inverse cosecant.
    acsch       - Inverse hyperbolic cosecant.
    cot         - Cotangent.
    coth        - Hyperbolic cotangent.
    acot        - Inverse cotangent.
    acoth       - Inverse hyperbolic cotangent.
 
  Exponential.
    exp         - Exponential.
    log         - Natural logarithm.
    log10       - Common (base 10) logarithm.
    log2        - Base 2 logarithm and dissect floating point number.
    pow2        - Base 2 power and scale floating point number.
    sqrt        - Square root.
    nextpow2    - Next higher power of 2.
 
  Complex.
    abs         - Absolute value.
    angle       - Phase angle.
    conj        - Complex conjugate.
    imag        - Complex imaginary part.
    real        - Complex real part.
    unwrap      - Unwrap phase angle.
    isreal      - True for real array.
    cplxpair    - Sort numbers into complex conjugate pairs.
 
  Rounding and remainder.
    fix         - Round towards zero.
    floor       - Round towards minus infinity.
    ceil        - Round towards plus infinity.
    round       - Round towards nearest integer.
    mod         - Modulus (signed remainder after division).
    rem         - Remainder after division.
    sign        - Signum.

    To use any of them ( for example) if you typed at the command prompt

    help sinh

Matlab will respond on its description and usage
Note that X can be a MATRIX

SIN    Sine.
    SIN(X) is the sine of the elements of X.

    Special Math functions

Typing     help specfun  at the prompt will give you a list of these functions
Specialized math functions.
 
  Specialized math functions.
    airy        - Airy functions.
    besselj     - Bessel function of the first kind.
    bessely     - Bessel function of the second kind.
    besselh     - Bessel functions of the third kind (Hankel function).
    besseli     - Modified Bessel function of the first kind.
    besselk     - Modified Bessel function of the second kind.
    beta        - Beta function.
    betainc     - Incomplete beta function.
    betaln      - Logarithm of beta function.
    ellipj      - Jacobi elliptic functions.
    ellipke     - Complete elliptic integral.
    erf         - Error function.
    erfc        - Complementary error function.
    erfcx       - Scaled complementary error function.
    erfinv      - Inverse error function.
    expint      - Exponential integral function.
    gamma       - Gamma function.
    gammainc    - Incomplete gamma function.
    gammaln     - Logarithm of gamma function.
    legendre    - Associated Legendre function.
    cross       - Vector cross product.
 
  Number theoretic functions.
    factor      - Prime factors.
    isprime     - True for prime numbers.
    primes      - Generate list of prime numbers.
    gcd         - Greatest common divisor.
    lcm         - Least common multiple.
    rat         - Rational approximation.
    rats        - Rational output.
    perms       - All possible permutations.
    nchoosek    - All combinations of N elements taken K at a time.
 
  Coordinate transforms.
    cart2sph    - Transform Cartesian to spherical coordinates.
    cart2pol    - Transform Cartesian to polar coordinates.
    pol2cart    - Transform polar to Cartesian coordinates.
    sph2cart    - Transform spherical to Cartesian coordinates.
    hsv2rgb     - Convert hue-saturation-value colors to red-green-blue.
    rgb2hsv     - Convert red-green-blue colors to hue-saturation-value.

Also try  help elmat
 

    Special functions - toolboxes

Each toolbox has a list of special functions that you can use

User defined functions

These are the functions you create.

These functions have a required format and are called function M-files

In Matlab M-files imply files (typically ascii ) saved with an extension .m

We will mostly use functions when we develop our program
 

Its time to look at program control in Matlab