Community Profile

Jonas Lundgren


26 total contributions since 2009

Professional Interests: Mathematics

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Contributions in
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Submitted


MCHECK
A Browser for the Code Analyzer

1 month ago | 3 downloads |

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SPLINEFIT
Fit a spline to noisy data.

4 months ago | 101 downloads |

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Alpha shapes
Alpha shape of 2D/3D point set.

5 years ago | 39 downloads |

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TSPSEARCH
Heuristic method for the Traveling Salesman Problem (TSP)

5 years ago | 23 downloads |

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ZEROBESS
Zeros of Bessel functions of 1st and 2nd kind plus zeros of the derivatives.

6 years ago | 4 downloads |

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KP01
Solves the 0-1 knapsack problem using preprocessing and dynamic programming.

6 years ago | 0 downloads |

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Calculate pi decimals
Calculate pi decimals with Machin's formula pi = 16*acot(5) - 4*acot(239)

6 years ago | 5 downloads |

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Re: integral equation with singularities and double integral
Hi, The Newton-Raphson solution below gives w = (78.1093 - 0.2275i). Another solution is w = (-78.1093 - 0.2275i). f = @(x,y,w)...

6 years ago | 4599 views

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Re: integral equation
A Newton-Raphson solution. Another root is close to (-2.6 - 1i). f = @(x,a) x.^2./(x+a+2)./(x+a-2)./(1+exp(2*x.^2)); df = @(x,a...

6 years ago | 3528 views

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Fractal curves
A collection of m-files to generate fractal curves in the complex plane.

6 years ago | 18 downloads |

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QUADGR
Gauss-Legendre quadrature with Richardson extrapolation.

6 years ago | 0 downloads |

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ALTSUM
Convergence acceleration of alternating series.

6 years ago | 1 download |

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Responded


Re: Using if else statement
k = find(v < 150); vlow = v(k); tlow = t(k); /Jonas

7 years ago | 2633 views

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Re: higher order spherical hankel functions
Hi Herwig, I get hn = 1.767281464772942e+008 -2.569212358491455e+024i The real part is actually "nothing" compared to the imagi...

7 years ago | 4855 views

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Re: How to optimise numerical integration?
Hi Alexander, A fast and accurate alternative using cumsum (as suggested by Roger Stafford) with a Gauss-Legendre quadrature (s...

7 years ago | 9848 views

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Re: code problem
Hi, You can use function handles: x0=0.1;y0=0.3;z0=0.2;eta0=1;p=1;j=1; L = sqrt(abs(4*p^2-8*p+4-j^2*p^2-2*j^2*p-j^2)); z = @(s)...

7 years ago | 1408 views

Responded


Re: HELP IF ME YOU CAN!!! Data reduction.
Hi Charles, If the first column is uniformly spaced then you need only the first and the last point of this column. Compress by:...

7 years ago | 2289 views

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Re: HELP IF ME YOU CAN!!! Data reduction.
Hi Charles, If the first column is uniformly spaced then you need only the first and the last point of this column. Compress by:...

7 years ago | 2289 views

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Re: random values
Wy not 15*sort(rand(100,1)) ? /Jonas

7 years ago | 6734 views

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Re: dblquad using a user specified quadrature function?
Richard, I have now updated quadgr to work properly with dblquad and triplequad. The new version of quadgr will soon be on the ...

7 years ago | 1826 views

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Re: How to make a 3D surface when z is not a explicit function of x and y
help griddata /Jonas

7 years ago | 2575 views

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Re: printing matrix
Example: % Generate matrix A = rand(7,3); % Get number of rows m = size(A,1); % Open a file for writing fid = fopen('matrix.txt...

7 years ago | 2044 views

Responded


Re: How to slove a matrix equation
Hi, Rewrite the equation: aVh - 1 = (aE - 11'V)x, where E is n by n identity matrix. /Jonas

7 years ago | 1755 views

Responded


Re: spline contour
Hi mona, You can try to increase the resolution and use griddata with cubic interpolation. Maybe this will give you a smoother c...

8 years ago | 3275 views

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Re: About Multiplication and convolution
At least it works the other way around "the transform of a convolution is the pointwise product of transforms" na = 3; nb = 5; ...

8 years ago | 8387 views