# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1085

[Latest](https://discourse.julialang.org/latest.md) · [Categories](https://discourse.julialang.org/categories.md) · [Tags](https://discourse.julialang.org/tags.md)

**Page:** 1086

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## [Modify colorbar in heatmap](https://discourse.julialang.org/t/modify-colorbar-in-heatmap/78544)

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**Author:** [@RickDW](https://discourse.julialang.org/u/RickDW)\
**Replies:** 2\
**Last updated:** [March 27, 2022, 3:02pm UTC](https://discourse.julialang.org/t/modify-colorbar-in-heatmap/78544 "2022-03-27T15:02:58Z")

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Hi, I’m trying to create an animation from a sequence of heatmaps, and I want to keep the upper and lower limits of the colorbar steady. I.e. if a value of say 0.5 is plotted using pure white in one frame I want 0.5 to m…

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## [Help I am new: Is this MDP righ?](https://discourse.julialang.org/t/help-i-am-new-is-this-mdp-righ/78522)

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**Author:** [@clrescobar](https://discourse.julialang.org/u/clrescobar)\
**Replies:** 10\
**Last updated:** [March 27, 2022, 2:17pm UTC](https://discourse.julialang.org/t/help-i-am-new-is-this-mdp-righ/78522 "2022-03-27T14:17:42Z")

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Hello, I am a new member. I have created the following MDP in otder to use Q-learning and Sarsa. When I try tu use q-learning it says that the mdp has no field indices. Could you please help me? Thank you! using POMDPs …

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## [One-dimensional NLS using MethodOfLines 'type Array has no field lhs\`](https://discourse.julialang.org/t/one-dimensional-nls-using-methodoflines-type-array-has-no-field-lhs/78543)

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**Author:** [@Ruvi\_Lecamwasam](https://discourse.julialang.org/u/Ruvi_Lecamwasam)\
**Replies:** 1\
**Last updated:** [March 27, 2022, 12:27pm UTC](https://discourse.julialang.org/t/one-dimensional-nls-using-methodoflines-type-array-has-no-field-lhs/78543 "2022-03-27T12:27:26Z")

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I’m trying to solve the one-dimensional nonlinear Schrodinger equation using MethodOfLines. I looked at the code on the docs: http://methodoflines.sciml.ai/dev/tutorials/brusselator/, and adapted it as: using ModelingTo…

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## [How to interrupt async tasks?](https://discourse.julialang.org/t/how-to-interrupt-async-tasks/77745)

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**Author:** [@melonedo](https://discourse.julialang.org/u/melonedo)\
**Replies:** 7\
**Last updated:** [March 27, 2022, 11:26am UTC](https://discourse.julialang.org/t/how-to-interrupt-async-tasks/77745 "2022-03-27T11:26:53Z")

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Suppose I have a few tasks synchronized by @sync and @async as show below: running = true function task() i = 0 while running println(i+=1) sleep(1) end end @sync begin @async task() …

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## [Merge where date ranges match](https://discourse.julialang.org/t/merge-where-date-ranges-match/78509)

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**Author:** [@rocco\_sprmnt21](https://discourse.julialang.org/u/rocco_sprmnt21)\
**Replies:** 4\
**Last updated:** [March 27, 2022, 11:15am UTC](https://discourse.julialang.org/t/merge-where-date-ranges-match/78509 "2022-03-27T11:15:30Z")

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“I have two tables that need to be combined. One table contains basic information about deals and another table information about the associated products.Each row consists of a state a deal was in from Start Date Deal to…

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## [Revisiting dedispersion](https://discourse.julialang.org/t/revisiting-dedispersion/78500)

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**Author:** [@Ujjwal\_Panda](https://discourse.julialang.org/u/Ujjwal_Panda)\
**Replies:** 4\
**Last updated:** [March 26, 2022, 3:16pm UTC](https://discourse.julialang.org/t/revisiting-dedispersion/78500 "2022-03-26T15:16:44Z")

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Hey folks :grin: ! Last time I asked for some performance tips on a code that was trying to implement the operation of dedispersion in Julia. Unfortunately, that code turned out to be incorrect. The code now up on the re…

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## [Extremely slow n-th root of float](https://discourse.julialang.org/t/extremely-slow-n-th-root-of-float/78534)

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**Author:** [@goerz](https://discourse.julialang.org/u/goerz)\
**Replies:** 11\
**Last updated:** [March 27, 2022, 5:23am UTC](https://discourse.julialang.org/t/extremely-slow-n-th-root-of-float/78534 "2022-03-27T05:23:18Z")

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I’m benchmarking an algorithm translated from Fortran, doing something similar to Expokit.expmv – evaluate the result of exponentiation a matrix and applying it to a vector, by expanding the exp into a polynomial series. …

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## [Python to Julia: Boolean Optimization](https://discourse.julialang.org/t/python-to-julia-boolean-optimization/78062)

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**Author:** [@YummyPampers2](https://discourse.julialang.org/u/YummyPampers2)\
**Replies:** 11\
**Last updated:** [March 27, 2022, 3:36am UTC](https://discourse.julialang.org/t/python-to-julia-boolean-optimization/78062 "2022-03-27T03:36:28Z")

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Hello Julians: I am looking to find the lowest energy state for the following system: (5x\_a) - (0.1x\_0) - (2x\_a\*x\_0) - 1.5 Using the following truth table: x\_a | x\_0 0 | | 0 0 | | 1 1 | | 0 1 | |…

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## [How do I interpret this error?](https://discourse.julialang.org/t/how-do-i-interpret-this-error/78537)

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**Author:** [@bwanab](https://discourse.julialang.org/u/bwanab)\
**Replies:** 0\
**Last updated:** [March 27, 2022, 1:20am UTC](https://discourse.julialang.org/t/how-do-i-interpret-this-error/78537 "2022-03-27T01:20:08Z")

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I can’t figure what this means. It looks like it says it can’t find exactly what it’s seeing as the closest candidate. julia\> ThinkStats.probs(t) ERROR: MethodError: no method matching probs(::Main.ThinkStats.CatDist) …

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## [Proper way to initiate an array with \`missing\`](https://discourse.julialang.org/t/proper-way-to-initiate-an-array-with-missing/8695)

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**Author:** [@floswald](https://discourse.julialang.org/u/floswald)\
**Replies:** 10\
**Last updated:** [March 26, 2022, 11:23pm UTC](https://discourse.julialang.org/t/proper-way-to-initiate-an-array-with-missing/8695 "2022-03-26T23:23:21Z")

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pretty simple question with no documentation that I could find. is this the right way to get a 3x1 array of missings that at some point I may want to fill with with Int? julia\> x = Union{Int64, Missings.Missing}\[missing…

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## [Probabilistic bounds-checking idea, to retain more (probabilistic) safety, and retaining most of the speed](https://discourse.julialang.org/t/probabilistic-bounds-checking-idea-to-retain-more-probabilistic-safety-and-retaining-most-of-the-speed/78515)

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**Author:** [@Palli](https://discourse.julialang.org/u/Palli)\
**Replies:** 2\
**Last updated:** [March 26, 2022, 8:23pm UTC](https://discourse.julialang.org/t/probabilistic-bounds-checking-idea-to-retain-more-probabilistic-safety-and-retaining-most-of-the-speed/78515 "2022-03-26T20:23:16Z")

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First, I like Julia’s approach to bounds checking, it seems ideal, better than most, in fact all, languages I know of. My own idea: @inbounds could be relaxed to check say every 4th loop iteration (configurable by the u…

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## [Julia 3 times slower than Fortran reading integer data from ASCII file](https://discourse.julialang.org/t/julia-3-times-slower-than-fortran-reading-integer-data-from-ascii-file/78516)

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**Author:** [@jman87](https://discourse.julialang.org/u/jman87)\
**Replies:** 14\
**Last updated:** [March 26, 2022, 7:20pm UTC](https://discourse.julialang.org/t/julia-3-times-slower-than-fortran-reading-integer-data-from-ascii-file/78516 "2022-03-26T19:20:13Z")

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Hey all, I’ve been dabbling with Julia since the 0. days. Up to point I haven’t had any real performance issues, but am now needing to read in some fairly large size files (think finite element / mesh data with millions …

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## [Optimisations for loops of known size at compile time](https://discourse.julialang.org/t/optimisations-for-loops-of-known-size-at-compile-time/78474)

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**Author:** [@Luapulu](https://discourse.julialang.org/u/Luapulu)\
**Replies:** 3\
**Last updated:** [March 25, 2022, 6:05pm UTC](https://discourse.julialang.org/t/optimisations-for-loops-of-known-size-at-compile-time/78474 "2022-03-25T18:05:29Z")

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Say I write a function like function func(n, ::Val{N}) where N s = 0 for i in 1:n for j in 1:N # some kind of logic here, e.g. s += i \* j end end return s end doe…

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## [Organize the output of a mathematical model](https://discourse.julialang.org/t/organize-the-output-of-a-mathematical-model/78378)

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**Author:** [@haniaitizem](https://discourse.julialang.org/u/haniaitizem)\
**Replies:** 4\
**Last updated:** [March 26, 2022, 5:28pm UTC](https://discourse.julialang.org/t/organize-the-output-of-a-mathematical-model/78378 "2022-03-26T17:28:27Z")

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Hello I have find a matrix q\[j,i,k\] at the end of my work, it represent the quantity of product k that should be ordered by client i from the plant j , I want to organize this output in a table in the row I find the plan…

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## [Jump using \`max(x...)\` where x is a matrix?](https://discourse.julialang.org/t/jump-using-max-x-where-x-is-a-matrix/78451)

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**Author:** [@floswald](https://discourse.julialang.org/u/floswald)\
**Replies:** 6\
**Last updated:** [March 26, 2022, 4:35pm UTC](https://discourse.julialang.org/t/jump-using-max-x-where-x-is-a-matrix/78451 "2022-03-26T16:35:01Z")

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I need to revive a previously asked question. I have a problem that involves evaluating the exp function over an array of variables and I want to avoid huge values by centering those variables before appplying exp. I get…

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## [Random draws of multivariate normal with positive semi-definite covariance matrix](https://discourse.julialang.org/t/random-draws-of-multivariate-normal-with-positive-semi-definite-covariance-matrix/78493)

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**Author:** [@AAL](https://discourse.julialang.org/u/AAL)\
**Replies:** 4\
**Last updated:** [March 26, 2022, 3:47pm UTC](https://discourse.julialang.org/t/random-draws-of-multivariate-normal-with-positive-semi-definite-covariance-matrix/78493 "2022-03-26T15:47:52Z")

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I am trying to generate random draws from a multivariate normal distribution with positive semi-definite covariance matrices. The Distributions.jl MvNormal only handles positive definite covariance matrices and throws an…

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## [SubArray -selecting same combination of rows from 2 arrays](https://discourse.julialang.org/t/subarray-selecting-same-combination-of-rows-from-2-arrays/78405)

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**Author:** [@VD\_19](https://discourse.julialang.org/u/VD_19)\
**Replies:** 11\
**Last updated:** [March 26, 2022, 3:19pm UTC](https://discourse.julialang.org/t/subarray-selecting-same-combination-of-rows-from-2-arrays/78405 "2022-03-26T15:19:45Z")

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Hi, I have 2 arrays and I want to make subarrays by selecing a combination of 2 rows from each but the selected index should be the same. e.g A = \[1 1 1 1 ;2 2 2 2 ;3 3 3 3 ;4 4 4 4 4 \] and B = \[5 5 5 5; 6 6 6 6; 7 7 …

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## [JuliaCon 2022 CFP deadline now just ~1 week away (as of March 26th)](https://discourse.julialang.org/t/juliacon-2022-cfp-deadline-now-just-1-week-away-as-of-march-26th/78513)

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**Author:** [@logankilpatrick](https://discourse.julialang.org/u/logankilpatrick)\
**Replies:** 0\
**Last updated:** [March 26, 2022, 1:59pm UTC](https://discourse.julialang.org/t/juliacon-2022-cfp-deadline-now-just-1-week-away-as-of-march-26th/78513 "2022-03-26T13:59:19Z")

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Folks, a quick reminder that the JuliaCon 2022 CFP deadline is now less than a week away. You can learn more on the conference submission website pretalx: JuliaCon 2022 (Times are UTC) :: pretalx Don’t wait until the la…

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## [JuliaCon 2022 Tickets, Call for Proposals (CFP), and Community Prize Nominations](https://discourse.julialang.org/t/juliacon-2022-tickets-call-for-proposals-cfp-and-community-prize-nominations/76864)

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**Author:** [@mfh](https://discourse.julialang.org/u/mfh)\
**Replies:** 3\
**Last updated:** [March 26, 2022, 1:55pm UTC](https://discourse.julialang.org/t/juliacon-2022-tickets-call-for-proposals-cfp-and-community-prize-nominations/76864 "2022-03-26T13:55:29Z")

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Dear people of Julia the JuliaCon 2022 Call for Proposals (CfP) is now open as well as conference registration! The JuliaCon 2022 organising team kindly invites you to submit proposals for talks, workshops, minisymposi…

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## [Problem with package Plots](https://discourse.julialang.org/t/problem-with-package-plots/78511)

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**Author:** [@Soldalma](https://discourse.julialang.org/u/Soldalma)\
**Replies:** 0\
**Last updated:** [March 26, 2022, 12:34pm UTC](https://discourse.julialang.org/t/problem-with-package-plots/78511 "2022-03-26T12:34:15Z")

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I have to run using Plots to run code that calls the Plots package. When I do that I get a message. The package still runs, the charts are generated normally. Still, something is not working properly. It would be best t…

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## [Nonlinear curve fitting with weights with LsqFit](https://discourse.julialang.org/t/nonlinear-curve-fitting-with-weights-with-lsqfit/78478)

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**Author:** [@achjaj](https://discourse.julialang.org/u/achjaj)\
**Replies:** 10\
**Last updated:** [March 26, 2022, 12:22pm UTC](https://discourse.julialang.org/t/nonlinear-curve-fitting-with-weights-with-lsqfit/78478 "2022-03-26T12:22:52Z")

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Hello, I need to fit the exponential decay law to some data with weights. I tried to use LsqFit.jl, however the standard\_errors function returns too low values. I discovered it by comparing my results with my friend and…

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## [Is \`InMemoryDatasets.create\_sysimage\` documented anywhere?](https://discourse.julialang.org/t/is-inmemorydatasets-create-sysimage-documented-anywhere/78246)

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**Author:** [@xinchin](https://discourse.julialang.org/u/xinchin)\
**Replies:** 4\
**Last updated:** [March 26, 2022, 11:10am UTC](https://discourse.julialang.org/t/is-inmemorydatasets-create-sysimage-documented-anywhere/78246 "2022-03-26T11:10:41Z")

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@sl-solution I see there’s a function in your package (not exported) and I think it is for creating sysimage? is it documented somewhere which I can look at?

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## [Dataframe Filter](https://discourse.julialang.org/t/dataframe-filter/78491)

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**Author:** [@janilin](https://discourse.julialang.org/u/janilin)\
**Replies:** 6\
**Last updated:** [March 26, 2022, 7:38am UTC](https://discourse.julialang.org/t/dataframe-filter/78491 "2022-03-26T07:38:39Z")

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Hi! I was trying to filter data and view the result of some selective columns, but can’t figure out. I created a dataframe first, using DataFrames df = DataFrame( name = \["a", "b", "c", "d"\], quiz\_1 = \[14,15,…

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## [Tell julia where R is](https://discourse.julialang.org/t/tell-julia-where-r-is/78499)

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**Author:** [@wub7quxa](https://discourse.julialang.org/u/wub7quxa)\
**Replies:** 2\
**Last updated:** [March 26, 2022, 5:27am UTC](https://discourse.julialang.org/t/tell-julia-where-r-is/78499 "2022-03-26T05:27:46Z")

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I run Julia in Jupyter on AWS Amazon SageMaker, where it is installed using anaconda. R Jupyter notebooks work as well, so clearly R is installed. “add RCall” in Julia’s package manager succeeds. But when I do “using RCa…

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## [Type-instability because of @threads boxing variables](https://discourse.julialang.org/t/type-instability-because-of-threads-boxing-variables/78395)

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**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 23\
**Last updated:** [March 25, 2022, 11:38pm UTC](https://discourse.julialang.org/t/type-instability-because-of-threads-boxing-variables/78395 "2022-03-25T23:38:29Z")

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See Type-instability because of @threads boxing variables - #12 by lmiq for a more precise description of the problem. Why are allocations occurring (or being reported, at least, by @allocated) in this example, sort of…

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## [Can I decrease allocations here?](https://discourse.julialang.org/t/can-i-decrease-allocations-here/78021)

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**Author:** [@fredrikpaues](https://discourse.julialang.org/u/fredrikpaues)\
**Replies:** 18\
**Last updated:** [March 25, 2022, 2:40pm UTC](https://discourse.julialang.org/t/can-i-decrease-allocations-here/78021 "2022-03-25T14:40:53Z")

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I’m trying to further optimize performance-critical function that locates values on a grid. Here I have tried using that the values will be sorted. And the bulk of the code is fast and has only 3 allocations, but then th…

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## [MVN CDF -- have it coded, need help getting integrating into Distributions.jl](https://discourse.julialang.org/t/mvn-cdf-have-it-coded-need-help-getting-integrating-into-distributions-jl/38631)

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**Author:** [@blackeneth](https://discourse.julialang.org/u/blackeneth)\
**Replies:** 18\
**Last updated:** [March 25, 2022, 7:43pm UTC](https://discourse.julialang.org/t/mvn-cdf-have-it-coded-need-help-getting-integrating-into-distributions-jl/38631 "2022-03-25T19:43:33Z")

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Summary I have written a Julia function to compute the Multivariate Normal integral. I need a partner who is an expert in Distributions.jl to properly integrate it into the code base. Introduction I have written a fu…

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## [Why can't I use LaTeX in makie? \[SOLVED\]](https://discourse.julialang.org/t/why-cant-i-use-latex-in-makie-solved/78470)

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**Author:** [@Amartins](https://discourse.julialang.org/u/Amartins)\
**Replies:** 5\
**Last updated:** [March 25, 2022, 6:49pm UTC](https://discourse.julialang.org/t/why-cant-i-use-latex-in-makie-solved/78470 "2022-03-25T18:49:08Z")

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I’m trying to understand why my code isn’t working and I can’t use LaTeX in my Makie graph. Can someone help me?

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## [ForwardDiff and Zygote cannot automatically differentiate (AD) function from C^n to R that uses FFT](https://discourse.julialang.org/t/forwarddiff-and-zygote-cannot-automatically-differentiate-ad-function-from-c-n-to-r-that-uses-fft/52440)

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**Author:** [@tholdem](https://discourse.julialang.org/u/tholdem)\
**Replies:** 23\
**Last updated:** [March 25, 2022, 6:28pm UTC](https://discourse.julialang.org/t/forwarddiff-and-zygote-cannot-automatically-differentiate-ad-function-from-c-n-to-r-that-uses-fft/52440 "2022-03-25T18:28:24Z")

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I’ve encountered so many bugs using ForwardDiff and Zygote to do automatic differentiation for my objective function that takes complex vector as input and outputs a real number. I don’t think I have the expertise to deb…

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## [Regression plots usin Makie.jl](https://discourse.julialang.org/t/regression-plots-usin-makie-jl/78485)

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**Author:** [@bicepjai](https://discourse.julialang.org/u/bicepjai)\
**Replies:** 0\
**Last updated:** [March 25, 2022, 6:24pm UTC](https://discourse.julialang.org/t/regression-plots-usin-makie-jl/78485 "2022-03-25T18:24:35Z")

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There are examples for plotting linear regression using Tutorial 🐧 · Algebra of Graphics ,but i lose all the customization with GitHub - JuliaPlots/Makie.jl: High level plotting on the GPU. Thanks for amazing plotting …

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