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2016-07-04 05:55:39 +0200 | commented answer | numerical computation of roots (maple equivalent of fsolve) of a system of nonlinear equations with multiple variables parameters Hey thanks! Is there a way to try out multiple guesses(in an array) for multiple variables? Or any function that can do away with initial guesses or set a boundary of solutions within an interval? |

2016-07-03 19:02:15 +0200 | asked a question | numerical computation of roots (maple equivalent of fsolve) of a system of nonlinear equations with multiple variables parameters Hi All, the following is my code: I tried using Sage "solve" to analytically solve the system of equations. I got a "FloatingPointError: Floating point exception" I thought of ways to get round this exception by 1) using log and exp in my math equations -- I can't work round this 2) I have no idea how to create exceptions for this since I can't access the sub-solutions while the solutions are still underway 3)Then I tried maxima.solve --> no roots could be found Maybe, this problem can't be solved analytically, so I thought maybe I could do so numerically. Hence my following question, I can only find functions that tackle univariate equations. Is there a sage equivalent of maple's f-solve which numerically computes all roots of multivariate system of nonlinear equations without the need of initial conditions? Thanks a lot! I would really appreciate this Rgds Samantha |

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2016-06-30 18:02:26 +0200 | asked a question | why green bar disappears prematurely, my codes have not finished running Hi guys Above is my question. I have long calculations to do on Sage, however the green bar disappears, while the '/' and '\' still alternates in my webpage tab on mac safari and the solutions(graph) have yet to appear. Any idea? Thanks! Samantha |

2016-06-30 17:57:42 +0200 | answered a question | Convert all complex numbers in array/matrix to value 0 or remove these numbers I did the following to solve this: 1) after solution and appending to lists, I stack lists into matrix 2) convert type from object to 'float64' 3) start a conditional to convert all terms with imag(x) != 0 into nan 4) do a mask to eliminate all rows(axis=1) that contains any term that gives true to isnan() |

2016-06-20 03:57:42 +0200 | commented question | Convert all complex numbers in array/matrix to value 0 or remove these numbers 1)I did a "solve" on 2 nonlinear equations with variables var1 and var2. z = solve
2)I made 2 empty lists : var1_y = [], var2_y = []
then i appended the var 1 and var 2 solutions separately
for solution in z:
var1_y.append(var1.subs(solution))
var2_y.append(var2.subs(solution))
3) then I combine them into matrix. How do I delete the rows with complex no? Thx!
var1_y2 = matrix(var1_y).transpose()
var2_y2 = matrix(var2)y).transpose()
A = var1_y2.augment(var2_y2)
[ 2 0]
[ -1/10 0]
[0.5186911103074608 - 0.8859791354693165 |

2016-06-19 17:17:17 +0200 | asked a question | Convert all complex numbers in array/matrix to value 0 or remove these numbers Hi all I'm new to sagemath, approximately 2 week-old. How do you convert all complex numbers in a nested array to value 0 or NaN? Or to remove these numbers from the array/matrix(which is eventually what I want to achieve in the end)? Thanks for your help! Rgds Sam |

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