First
You can force MATLAB to write its explicit form using MaxDegree with solve()
syms x
equ = x^3 + (29*x^2)/100 - (1351*x)/100 + 359/50 == 0
Spectrum = solve(equ, x, 'MaxDegree', 3)
Result
Spectrum =
406141/(90000*(- 114584939/27000000 + (1200000000^(1/2)*88664127737^(1/2)*1i)/1200000000)^(1/3)) + ((1200000000^(1/2)*88664127737^(1/2)*1i)/1200000000 - 114584939/27000000)^(1/3) - 29/300
- (3^(1/2)*(406141/(90000*(- 114584939/27000000 + (1200000000^(1/2)*88664127737^(1/2)*1i)/1200000000)^(1/3)) - ((1200000000^(1/2)*88664127737^(1/2)*1i)/1200000000 - 114584939/27000000)^(1/3))*1i)/2 - 406141/(180000*(- 114584939/27000000 + (1200000000^(1/2)*88664127737^(1/2)*1i)/1200000000)^(1/3)) - ((1200000000^(1/2)*88664127737^(1/2)*1i)/1200000000 - 114584939/27000000)^(1/3)/2 - 29/300
(3^(1/2)*(406141/(90000*(- 114584939/27000000 + (1200000000^(1/2)*88664127737^(1/2)*1i)/1200000000)^(1/3)) - ((1200000000^(1/2)*88664127737^(1/2)*1i)/1200000000 - 114584939/27000000)^(1/3))*1i)/2 - 406141/(180000*(- 114584939/27000000 + (1200000000^(1/2)*88664127737^(1/2)*1i)/1200000000)^(1/3)) - ((1200000000^(1/2)*88664127737^(1/2)*1i)/1200000000 - 114584939/27000000)^(1/3)/2 - 29/300
Second
Or you can get output in variable precision numeric format
syms x
equ = x^3 + (29*x^2)/100 - (1351*x)/100 + 359/50 == 0
Spectrum = vpa(solve(equ, x, 'MaxDegree', 3))
Result
Spectrum =
3.2163511711964122946143841774131 + 3.6734198463196484624023016788195e-40i
- 4.056644260843024929305472877667 + 3.6734198463196484624023016788195e-40i
0.55029308964661263469108870025384 - 7.346839692639296924804603357639e-40i
The solution has a tiny complex part, probably due to numeric errors. You can extract the real part like this
real(Spectrum)
Third
Directly convert to floating-point format using double
syms x
equ = x^3 + (29*x^2)/100 - (1351*x)/100 + 359/50 == 0
Spectrum = double(solve(equ, x, 'MaxDegree', 3))
Spectrum = real(Spectrum)
Result
Spectrum =
3.2164
-4.0566
0.5503
