naginterfaces.library.blas.dcsg

naginterfaces.library.blas.dcsg(t)[source]

dcsg reconstructs the parameters and of a real plane rotation from the tangent of that rotation.

For full information please refer to the NAG Library document for f06bc

https://www.nag.com/numeric/nl/nagdoc_28.7/flhtml/f06/f06bcf.html

Parameters
tfloat

The value , the tangent of the rotation.

Returns
cfloat

The value , the cosine of the rotation.

sfloat

The value , the sine of the rotation.

Notes

No equivalent traditional C interface for this routine exists in the NAG Library.

dcsg reconstructs the parameters and of a real plane rotation from the value of the tangent , as returned by drotgc():

so that and has the same sign as .

If , where is the machine precision, the function sets and ; if , the function sets and .