forked from personal/squiggle.c
Increase clarity of README and fix typos
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README.md
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README.md
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@ -61,7 +61,7 @@ The motte:
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The bailey:
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The bailey:
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- I've been hacking at this project for a while now, and I think I have a good grasp of its correctness and limitations. I've tried Nim and Zig, and I prefer C so far.
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- I've been hacking at this project for a while now, and I think I have a good grasp of its correctness and limitations. I've tried Nim and Zig, and I prefer C so far.
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- I think the core interface is not likely to change much stable, though I've been changing the interface for parallelism and for getting confidence intervals.
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- I think the core interface is not likely to change much, though I've recently changed the interface for parallelism and for getting confidence intervals.
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- I am using this code for a few important consulting projects, and I trust myself to operate it correctly.
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- I am using this code for a few important consulting projects, and I trust myself to operate it correctly.
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This project is released under the MIT license, a permissive open-source license. You can see it in the LICENSE.txt file.
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This project is released under the MIT license, a permissive open-source license. You can see it in the LICENSE.txt file.
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@ -103,7 +103,7 @@ c_samples = sq.sample(c, 10)
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print(c_samples)
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print(c_samples)
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```
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```
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Should `c` be equal to `2`? or should it be equal to 2 times the expected distribution of the ratio of two independent draws from a (`2 * a/a`, as it were)?
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Should `c` be equal to `2`? or should it be equal to 2 times the expected distribution of the ratio of two independent draws from a (`2 * a/a`, as it were)? You don't know, because you are not operating on samples, you are operating on magical objects whose internals are hidden from you.
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In squiggle.c, this ambiguity doesn't exist, at the cost of much greater overhead & verbosity:
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In squiggle.c, this ambiguity doesn't exist, at the cost of much greater overhead & verbosity:
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@ -175,9 +175,9 @@ Hint: See examples/more/13_parallelize_min
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### Note on sampling strategies
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### Note on sampling strategies
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Right now, I am drawing samples from a random number generator. It requires some finesse, particularly when using parallelism. But it works fine.
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Right now, I am drawing samples using a random number generator. It requires some finesse, particularly when using parallelism. But it works fine.
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But..., what if we could do something more elegant, more ingenious. In particular, what if instead of drawing samples, we had a mesh of equally spaced points in the range of floats. Then we could, for a given number of samples, better estimate the, say, mean of the distribution we are trying to model...
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But..., what if we could do something more elegant, more ingenious? In particular, what if instead of drawing samples, we had a mesh of equally spaced points in the range of floats? Then we could, for a given number of samples, better estimate the, say, mean of the distribution we are trying to model...
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The problem with that is that if we have some code like:
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The problem with that is that if we have some code like:
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@ -195,7 +195,7 @@ Then this doesn't work, because the values of a and b will be correlated: when a
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```C
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```C
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double* model(int n_samples){
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double* model(int n_samples){
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double* xs = malloc(n_samples);
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double* xs = malloc((size_t)n_samples * sizeof(double));
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for(int i_mesh=0; i_mesh < sqrt(n_samples); i_mesh++){
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for(int i_mesh=0; i_mesh < sqrt(n_samples); i_mesh++){
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for(int j_mesh=0; j_mesh < sqrt(n_samples); j_mesh++){
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for(int j_mesh=0; j_mesh < sqrt(n_samples); j_mesh++){
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double a = sample_to(1, 10, i_mesh);
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double a = sample_to(1, 10, i_mesh);
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@ -207,7 +207,7 @@ double* model(int n_samples){
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```
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```
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But that requires us to encode the shape of the model into the sampling function. It leads to an ugly nesting of for loops. It is a more complex approach. It is not [grug-brained](https://grugbrain.dev/). So every now and then I have to remind myself that this is not the way.
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But that requires us to encode the shape of the model into the sampling function. It leads to an ugly nesting of for loops. It is a more complex approach. It is not [grug-brained](https://grugbrain.dev/). So every now and then I have to remember that this is not the way.
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### Tests and the long tail of the lognormal
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### Tests and the long tail of the lognormal
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@ -367,7 +367,7 @@ Overall, I'd describe the error handling capabilities of this library as pretty
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### Other gotchas
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### Other gotchas
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- Even though the C standard is ambiguous about this, this code assumes that doubles are 64 bit precision (otherwise the xorshift should be different).
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- Even though the C standard is ambiguous about this, this code assumes that doubles are 64 bit precision (otherwise the xorshift code should be different).
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## Related projects
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## Related projects
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