Until Typst implements the feature, an incomplete & hacky interim sol…

…ution for braket etc.

Not satisfactory, until Typst resolves typst/typst#240

This interim solution can handle
$ mel(u,M,v) mel(u,vec(U,V),v), mel(vec(U,V),M,v) $
but not something like
$ mel(u,vec(U,V,W),v) mel(vec(U,V,W),M,v) $

Motivated by #16

README.md

@@ -99,6 +99,8 @@ explore the design together. Some features might warrant a package on its own.
 [physica-manual.pdf](https://github.com/Leedehai/typst-physics/blob/master/physica-manual.pdf). This does not scale well. I plan to add programmatic
 testing by comparing rendered pictures with golden images.
 
+* Please nudge Typst maintainers to resolve https://github.com/typst/typst/issues/240 by scaling up given glyphs in the middle of [`lr()`](https://typst.app/docs/reference/math/lr#functions-lr) :grinning:
+
 ## License
 
 * Code: the [MIT License](LICENSE.txt).

physica-manual.typ

@@ -1,5 +1,6 @@
 // Copyright 2023 Leedehai
 // This document is shared under the Creative Commons BY-ND 4.0 license.
+#import "physica.typ": *
 
 #let version = "0.8.1"
 
@@ -52,8 +53,6 @@ This manual itself was generated using the Typst CLI and the `physica` package,
 
 With `typst`'s #linkurl("package management", "https://github.com/typst/packages"):
 
-#import "physica.typ": *
-
 ```typst
 #import "@preview/physica:0.8.1": *
 

physica.typ

@@ -344,6 +344,15 @@
 #let bra(f) = $lr(angle.l #f|)$
 #let ket(f) = $lr(|#f angle.r)$
 
+// Quadratic interpolation that takes in a height in pt units.
+// Intended input-output pairs: {10.59,1},{23.01,0.8},{26.93,0.7}.
+// This is imperfect, hacky and has corner cases unresolved, but until
+// https://github.com/typst/typst/issues/240 is resolved there is no better way.
+// Motivated by https://github.com/Leedehai/typst-physics/issues/16
+#let __height_mul_factor(h) = {
+  -0.0005757 * h * h + 0.0032409 * h + 1.03024
+}
+
 // Credit: thanks to peng1999@ and szdytom@'s suggestions of measure() and
 // phantoms. The hack works until https://github.com/typst/typst/issues/240 is
 // addressed by Typst.
@@ -355,7 +364,9 @@
   let ket = args.at(1, default: bra)
 
   let height = measure($ bra ket $, styles).height;
-  let phantom = box(height: height * 0.8, width: 0pt, inset: 0pt, stroke: none);
+  let phantom = box(
+    height: height * __height_mul_factor(height.pt()),
+    width: 0pt, inset: 0pt, stroke: none);
   $ lr(angle.l bra lr(|phantom#h(0pt)) ket angle.r) $
 })
 
@@ -369,7 +380,9 @@
   let ket = args.at(1, default: bra)
 
   let height = measure($ bra ket $, styles).height;
-  let phantom = box(height: height * 0.8, width: 0pt, inset: 0pt, stroke: none);
+  let phantom = box(
+    height: height * __height_mul_factor(height.pt()),
+    width: 0pt, inset: 0pt, stroke: none);
   $ lr(bar.v bra#h(0pt)phantom angle.r)lr(angle.l phantom#h(0pt)ket bar.v) $
 })
 
@@ -382,7 +395,9 @@
 // we use the same hack as braket().
 #let matrixelement(n, M, m) = style(styles => {
   let height = measure($ #n #M #m $, styles).height;
-  let phantom = box(height: height * 0.8, width: 0pt, inset: 0pt, stroke: none);
+  let phantom = box(
+    height: height * __height_mul_factor(height.pt()),
+    width: 0pt, inset: 0pt, stroke: none);
   $ lr(angle.l #n lr(|#M#h(0pt)phantom|) #m angle.r) $
 })