Programmer Guide/Command Reference/EVAL/complex arithmetic

{{DISPLAYTITLE:complex arithmetic

Because the current version of the STx EVAL command do not support a complex data type, a package of functions is used to implement arithmetic and special handling for complex numbers.

The package consists of the functions:

cr2p, cr2len, cr2phi, cp2r, cget, cset, conj, ctrn, cdot, cmul, cmulv

Note:

• A complex number or complex scalar is a numerical object v with 2 rows and 1 column (a vector):

v[0] =	re (cartesian: real part) or len (polar: length)
v[1] =	im (cartesian: imaginary part) or phi (polar: phase)

• A complex vector with N elements is a numerical object v with 2N rows and 1 column (a vector):

v[2i] =	rei or reireal part (re) or length (len, polar)
v[1] =	imaginary part (im, cartesian) or phase (phi, polar)

• In general a numerical object containing N x M complex numbers (N>=1, M>=1), consists of 2N rows and M columns, because each complex number uses two cells of a row.
• If a numerical object containing N x M complex numbers, is converted element-wise to real numbers, the resulting object consists of N rows and M columns.

---

complex -> complex

xc	... any complex type
rc ..	... same complex type as xc

rc=cr2p(xc)

Convert xc from cartesian (real, imaginary) to polar (length, phase) format.

rc=cp2r(xc)

Convert xc from polar (length, phase) to cartesian (real, imaginary) format.

rc=conj(xc)

Conjugate xc; xc must be in cartesian format.

---

complex -> real

xc	... any complex type
r	... same real type as xc

r=cr2len(xc)

Compute length of xc; xc is stored in cartesian format.

r=cr2phi(xc)

Compute phase of xc; xc is stored in cartesian format.

r=cget(xc,0)

Get real part or length of xc (depends on format of xc).

r=cget(xc,1)

Get imaginary part or phase of xc (depends on format of xc).

---

real -> complex

x	... any real type
y	... same type as x
rc	... same complex type as x

rc=cset(x,y)

Combine elements of x (real part or length) and y (imaginary part or phase) to complex numbers.

---

multiplication (element-wise)

xc	... any complex type (re,im)
yc	... same complex type as 'xc'
n	... real or complex number (re,im)
result rc	... same complex type as xc

rc=cmul(xc,n)

rc=cmul(n,xc)

Multiply each element of xc with the real or complex number n.

rci,j = xci,j * n

rc=cmul(xc,yc)

Multiply xc and yc element by element.

rci,j = xci,j * yci,j

---

special functions

rcscalar=cdot(xcvector,ycvector)

Compute the dot product (inner product) of the two complex vectors xc and yc (both with N elements).

rc = sumi=0..N-1 (xci * yci) , i=0..N-1

rcmatrix=ctrn(xcmatrix)

Transposed the complex matrix xc.

rci,j = xcj,i

rcmatrix=cmulv(xcvector,ycvector)

Compute the tensor (or dyadic) product of the two complex vectors xc and yc.

rci,j = xci * ycj

rcvector=cmulv(xcvector,ycmatrix)

Compute the product of the complex vector xc (N elements) and the complex matrix yc (N rows, M columns).

rcj = sumi=0..N-1 (xci * yci,j) , j=0..M-1

rcvector=cmulv(xcmatrix,ycvector)

Compute the product of the complex matrix xc (N rows, M columns) and the complex vector yc (M elements).

rci = sumj=0..M-1 (xci,j * ycj) , i=0..N-1

rcmatrix=cmulv(xcmatrix,ycmatrix)

Compute the product of the complex NxM matrix xc and the complex MxL matrix yc. The result is the complex NxL matrix rc.

rci,k = sumj=0..M-1 (xci,j * ycj,i) , i=0..N-1 and k=0..L-1

See also

complex numbers, vvset, vvget, vv, fft, dft,

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