V thomas #634
V thomas #634
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Liikt
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| d[i] -= c[i] * d[i+1] | ||
| } | ||
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| return d |
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Returning something that you've also mutated as an input argument isn't good no matter the language. You should return d, remove mut for c and d, and make copies of those two input arrays.
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You are of course right. I changed it.
Thanks 👍
| println("[2.0 3.0 5.0][y] = [5.0]") | ||
| println("[0.0 3.0 6.0][z] = [3.0]") | ||
| println("has the solution:") | ||
| solve := thomas(a, b, mut c, mut d) |
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| solve := thomas(a, b, mut c, mut d) | |
| solution := thomas(a, b, mut c, mut d) |
is more descriptive to me.
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Can you revert your changes to |
| @@ -0,0 +1,35 @@ | |||
| fn thomas(a []f32, b []f32, c []f32, d []f32) []f32 { | |||
| mut new_c := c | |||
| mut new_d := d | |||
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This isn't actually making a copy.
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you are right. this just creates a new pointer, pointing to the old array.
this defeats the whole purpose of mut, as the current implementation of V mutates the original array as well.
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Yikes. Filed vlang/v#2548.
In the meantime, can you do it "by hand"? Write a function that, given an array, makes a new one, iterates over the old one pushing each item into the new one, then returns the new one?
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Meaning, while I acknowledge there is a compiler bug, we should implement the workaround anyway (at least for now) in the interest of safety.
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I asked Alex (the main dev) already about it. he knows and is currently reworking the memory stuff. after that is done this bug should be gone as well
This reverts commit bf91a89.
berquist
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berquist
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I'll take your word on it about the bug, plus the linked issue will let me know to re-test this. Everything else looks good.
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thomas algorithm in vlang