## STACK Documentation

Documentation home | Category index | Site map# The Greek Alphabet

Greek letters are transliterated using their English names. I.e.

```
[alpha,beta,gamma,delta,epsilon,zeta,eta,theta,iota,kappa,lambda,mu,nu,xi,omicron,pi,rho,sigma,tau,upsilon,phi,chi,psi,omega]
```

Upper case Greek letters have an upper-case English first letter. I.e.

```
[Alpha,Beta,Gamma,Delta,Epsilon,Zeta,Eta,Theta,Iota,Kappa,Lambda,Mu,Nu,Xi,Omicron,Pi,Rho,Sigma,Tau,Upsilon,Phi,Chi,Psi,Omega]
```

Many of the Greek letters already have a meaning in Maxima.

`beta`

: The beta function is defined as \(\gamma(a) \gamma(b)/\gamma(a+b)\).`gamma`

: The gamma function.`delta`

: This is the Dirac Delta function (only defined in Laplace).`zeta`

: This is the Riemann zeta function.`lambda`

: Defines and returns a lambda expression, i.e. an unnamed function.`psi`

: The derivative of 'log (gamma ())' of order ' +1', which has a strange syntax `psi[n](x)`

. It is also defined in the tensor package.

Note that by default, `psi`

requires arguments and any attempt to use this variable name without arguments will result in an error. For this reason we delete this function in STACK, and `psi`

becomes an unnamed variable.

The following are given a specific value by STACK.

`pi`

is defined to be the numeric constant which is the ratio of the diameter to the circumference of a circle. In Maxima this is normally`%pi`

, but STACK also defines the letter`pi`

to have this value.- In Maxima the numeric constant which represents the so-called golden mean, \((1 + \sqrt{5})/2\) is
`%phi`

.

## "Undefine" Maxima defaults

It is currently not possible to "undefine" function names and return them to variables.

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