Why do I get conj(L)

When I multiply 2 4X4 matrices one numeric the other alpha numeric say with L1,L2,L3, L4 why do I get the answer with cconj(L1,L2,L3,L4)? Also why do I get answers in fractions not decimal?

Answer 1

[Star Strider]

The Symbolic Math Toolbox assumes all variables are complex, so it adds the conj to be complete. Specifying that the variables are real in the syms declaration prevents that.

To convert the fractions to decimal fractions, use the vpa function. To always get decimal fractions, use the appropriate options in sympref. .

[Walter Roberson]

Symbolic Math toolbox does not ordinarily add conj() for matrix multiplication or element-by-element multiplication.

Answer 2

[Walter Roberson]

You probably used the ' operator on the symbolic vector. For example,

syms L [1 4]
A = [2 3; 4 5]/7

A = 2×2

0.2857 0.4286 0.5714 0.7143

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B = [L1 L2; L3 L4]

B = 

C = A*B

C = 

C = A*B'

C = 

●

whereas you might have wanted

D = A*B.'

D = 

To get the answer in decimal, either use

vpa(D, 10)

ans = 

or else use

sympref('FloatingPointOutput', true)

ans = logical
   0

D

D =