Multiline equation with alignment not rendered correctly in pdf export

[cpraveen]

Multiline equations like this

$$
a &= b \\
  &= c \\
  &= d
$$

renders correctly in html. I think they are wrapped in align.

But when I export to pdf, the alignments are ignored, and the equation is shown on single line.

$ myst -v
v1.3.20

[cpraveen]

E.g., see eq. (9) here https://cpraveen.github.io/numa/intro

and the same in exported pdf is attached in pic below

[rowanc1]

Are you using typst or latex for the export to PDF? Can you provide the output in either language and what you would expect?

You can wrap in a \begin{align*} I believe, does that fix things?

[cpraveen]

What I expect is to look as in the html output I have linked.

I am using latex. Using align will work, but I have too many equations using $$, and since it works in html, I hope it can be fixed in pdf output.

This is output from building pdf with latex, see messages related to intro.md file which is what I am showing in the html link above.

$ myst build intro.md --pdf    
📬 Performing exports:
   intro.md -> _build/exports/intro.pdf
⚠️  intro.md:90 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 5: u_0 &̲= 0 \\
- \frac{…
📖 Built intro.md in 599 ms.
📖 Built front.md in 597 ms.
📖 Built hiformula.md in 589 ms.
⛔️ potential.md container of kind undefined contains no valid content besides caption, legend
   Valid content types include image, referenced notebook cell, table, code, iframe, subfigure
⛔️ potential.md container of kind undefined contains no valid content besides caption, legend
   Valid content types include image, referenced notebook cell, table, code, iframe, subfigure
⚠️  potential.md unexpected figure content of type image found in legend node
⚠️  potential.md unexpected figure content of type image found in legend node
⚠️  potential.md missing heading depth 3
⚠️  potential.md missing heading depth 4
📖 Built potential.md in 590 ms.
⚠️  hermite.md missing heading depth 3
⚠️  hermite.md missing heading depth 4
⚠️  hermite.md:59 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 12: f[a,a,b,b] &̲= \frac{f[a,b,b…
⚠️  hermite.md:67 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 8: H_2(b) &̲= f(a) + (b-a)f…
📖 Built hermite.md in 589 ms.
📖 Built approx.md in 586 ms.
📖 Built integrate.md in 586 ms.
⚠️  newton_cotes.md:152 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 15: I(f) - I_n(f) &̲= I(f) - I(f_\e…
📖 Built newton_cotes.md in 586 ms.
⚠️  mid_point.md:49 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 60: …b}{2} \right) 
&̲= \half f''(\et…
📖 Built mid_point.md in 586 ms.
⚠️  gauss1.md:114 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 6: I(f) &̲= \int_{-1}^1 f…
📖 Built gauss1.md in 586 ms.
⚠️  opoly.md:133 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 24: …_{n+1},\phi_i} &̲= 0, \qquad 0 \…
⚠️  opoly.md:205 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 18: …p{\phi_n, x^n} &̲= \ip{\phi_n, \…
⚠️  opoly.md:237 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 51: … \phi_{n+1}(y) &̲= a_n (x-y) \ph…
⚠️  opoly.md:266 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 82: …ma_{0} (x-y)} 
&̲= \frac{(A_1 x …
📖 Built opoly.md in 586 ms.
⚠️  extquad.md missing heading depth 3
⚠️  extquad.md missing heading depth 4
📖 Built extquad.md in 585 ms.
⚠️  float.md:161 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 3: 0 &̲ \le x - \fl{x}…
⚠️  float.md:172 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 3: 0 &̲\le \frac{x - \…
⚠️  float.md:266 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 12: 1 + 2^{-t} &̲= [ (.10\ldots …
⚠️  float.md:273 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 18: …l{1 + 2^{-t}} =&̲ (.10\ldots 10)…
⚠️  float.md:282 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 13: 1 + \delta =&̲ [ (.10\ldots 0…
⚠️  float.md:740 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 13: \rho_{k+1} =&̲ \frac{\hats_{k…
⚠️  float.md:756 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 11: |\rho_1| =&̲ 0 \\
|\rho_2| …
⚠️  float.md:766 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 13: |\rho_n| \le&̲ (1 + \theta + …
⚠️  float.md:779 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 10: \hats_1 =&̲ x_1 \\
\hats_2…
⚠️  float.md:792 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 16: \hats_n - s_n =&̲ s_2 \epsilon_2…
⚠️  float.md:823 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 14: \err{\haty} =&̲ |y - \haty| \\…
📖 Built float.md in 722 ms.
📖 Built roots.md in 720 ms.
📖 Built bisect.md in 721 ms.
📖 Built newton.md in 721 ms.
📖 Built secant.md in 721 ms.
📖 Built fpiter.md in 721 ms.
📖 Built homotopy.md in 721 ms.
📖 Built interp.md in 720 ms.
📖 Built lagrange.md in 721 ms.
📖 Built barycentric.md in 720 ms.
⚠️  newton_interp.md:251 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 54: …dots,x_{k-1}] 
&̲= \sum_{j=0}^k …
⚠️  newton_interp.md:342 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 33: …x_N - x_{N-1}) &̲ f[x_0,x_1,\ldo…
📖 Built newton_interp.md in 721 ms.
📖 Built ppinterp.md in 719 ms.
⚠️  splines.md:94 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 7: s(x) =&̲ \frac{1}{6h_i}…
📖 Built splines.md in 719 ms.
⚠️  fourier.md:41 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 5: a_0 &̲= \frac{1}{2\pi…
📖 Built fourier.md in 719 ms.
⚠️  dft.md:289 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 46: …umfr |\hatu_k| &̲= \order{\frac{…
📖 Built dft.md in 720 ms.
📖 Built trapz.md in 719 ms.
📖 Built simpson.md in 719 ms.
📖 Built peano.md in 719 ms.
⚠️  gauss2.md:96 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 9: e_n(x) 
&̲= f(x) - H_n(x)…
⚠️  gauss2.md:181 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 26: …^n v_j p(z_j) 
&̲= \int_a^b w(x)…
📖 Built gauss2.md in 718 ms.
⚠️  squad.md:276 Wrapping with \begin{align*}
   KaTeX parse error: Expected 'EOF', got '&' at position 6: I_1 
&̲= \int_0^{\epsi…
📖 Built squad.md in 718 ms.
📖 Built aquad.md in 718 ms.
📚 Built 33 pages for export (including 32 dependencies) from /Volumes/Samsung_T5/Teaching/numa in 878 ms.
📑 Exported TeX in 16 ms, copying to _build/temp/mystLd2PBC/intro.tex
⛔️ intro.md 'frontmatter' missing required key: date (at intro.md)
🖨  Rendering PDF (default) to _build/temp/mystZs9S2F/intro.pdf
📄 Exported PDF (default) in 1.86 s, copying to _build/exports/intro.pdf
⛔️ _build/exports/intro.pdf LaTeX reported an error building your PDF (default) for intro.tex

[rowanc1]

Interesting - we do seem to wrap the equation in align* for the web, but do not update the source of the equation, so latex doesn't get those benefits.

This could likely be updated here to write back to the source.