Miscellaneous vector functions

Description

These functions provide the (Euclidean) length of a vector, the vector cross product or angle between two vectors.

Usage

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resolveVector(len, ...)

vectorLength(vector)

vectorCrossProduct(a, b)

angleBetweenVectors(v1, v2)

Arguments

len

The expected length of the vector.

vector, v1, v2

Numeric vectors of any length.

a, b

Numeric 3-vectors.

...

Elements of the vector, to be concatenated together.

Value

For vectorLength, the Euclidean norm or length of the specified vector, given by sqrt(sum(vector^2)). For vectorCrossProduct, the vector cross product of the two specified vectors; and for angleBetweenVectors, the angle (in radians) between the two specified vectors. The resolveVector function concatenates the values given in ...{}, and if the result is a vector of length len then it is returned. If not, NULL is returned.

Author(s)

Jon Clayden

References

Please cite the following reference when using TractoR in your work:

J.D. Clayden, S. Muñoz Maniega, A.J. Storkey, M.D. King, M.E. Bastin & C.A. Clark (2011). TractoR: Magnetic resonance imaging and tractography with R. Journal of Statistical Software 44(8):1-18. http://www.jstatsoft.org/v44/i08/.

See Also

crossprod for the matrix cross product.

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