as you have the pdf just look at the font menu in your pdf viewer or use the pdffonts commandline utility to list them all
– David CarlisleNov 24 '21 at 18:45
CharterBT-Roman and MathDesign-CH-Regular-Symbol-10 and related fonts mostly, set with TeXPadTeX on an iphone.
– David CarlisleNov 24 '21 at 18:50
@DavidCarlisle Thank you so much for your help! I can obtain similar effect with \usepackage[charter]{mathdesign} or \usepackage[charter,cal=cmcal]{mathdesign}.
– AkiraNov 24 '21 at 20:57
pdffontscommandline utility to list them all – David Carlisle Nov 24 '21 at 18:45\usepackage[charter]{mathdesign}or\usepackage[charter,cal=cmcal]{mathdesign}. – Akira Nov 24 '21 at 20:57