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StuartBruff23-Emerald V
23-Emerald V
June 23, 2015
Question

Sometimes multiplication is really complex ...

  • June 23, 2015
  • 1 reply
  • 2584 views

Every engineer, mathematician and scientist is born knowing that the vector dot product is the sum of the element-by-element multiplication of the components of the two vectors. But occasionally, when our brain isn't paying full attention, things don't work out as intended ...

Stuart

PS.  I blame Valery for this one.  If he hadn't posed that clock question, I wouldn't have tried to generalize it and spend a couple of minutes wondering why my previously fine power series expansion formula wasn't working when applied to complex number bases.

1 reply

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AlanStevens19-Tanzanite
19-Tanzanite
June 23, 2015

An interesting bug!  It appears that Mathcad takes the complex conjugate of the "z" vector before multiplying!  You can avoid the problem by replacing a*z in PowerDot Mul by aT*z  (where aT is the transpose of a).  Mathcad no longer bothers to take the complex conjugate!

Alan

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StuartBruff23-Emerald VAuthor
23-Emerald V
June 23, 2015

AlanStevens wrote:

An interesting bug!  It appears that Mathcad takes the complex conjugate of the "z" vector before multiplying!  You can avoid the problem by replacing a*z in PowerDot Mul by aT*z  (where aT is the transpose of a).  Mathcad no longer bothers to take the complex conjugate!

Interesting.  A bug?

Stuart

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