Some time ago, I gave recommendations for packages to use to produce output in Times roman fonts (and others that look nice with Times). Doing this has the downside that certain aspects of the Times math fonts are really ugly. In particular the sum operator and the calligraphy font look awful.

René van Bevern has a solution for using Computer Modern for \mathcal and \sum along with the mathptmx package.

Using his idea, I have a very similar solution for using the Latin Modern font family instead.

\SetMathAlphabet{\mathcal}{normal}{OMS}{lmsy}{m}{n}
\SetMathAlphabet{\mathcal}{bold}{OMS}{lmsy}{m}{n}
\SetSymbolFont{largesymbols}{normal}{OMX}{lmex}{m}{n}
\SetSymbolFont{largesymbols}{bold}{OMX}{lmex}{m}{n}

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