# spray-package

From spray v1.0-6
by Robin K S Hankin

##### Sparse arrays and multivariate polynomials

Functionality for sparse arrays, with emphasis on sparse arrays interpreted as multivariate polynomials.

- Keywords
- package

##### Details

Sparse arrays are a dictionary with keys being (unsigned) integer vectors, and values floats.

##### See Also

##### Examples

```
# NOT RUN {
# define a spray using a matrix of indices and a vector of values:
M <- matrix(sample(0:3,21,replace=TRUE),ncol=3)
a <- spray(M,sample(7))
# there are many pre-defined simple sprays:
b <- homog(3,4)
# arithmetic operators work:
a + 2*b
a - a*b^2/4
a+b
# we can sum over particular dimensions:
asum(a+b,1)
# differentiation is supported:
deriv(a^6,2)
# extraction and replacement work as expected:
b[1,2,1]
b[1,2,1,drop=TRUE]
b[diag(3)] <- 3
# }
```

*Documentation reproduced from package spray, version 1.0-6, License: GPL (>= 2)*

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