Changing Font Size in LibreOffice Math Formulas

LibreOffice Math provides dedicated commands to adjust the font size of distinct sections, terms, or individual characters within a single formula. By applying the size command alongside specific numerical values or arithmetic operators, you can scale selected components absolutely or relatively without altering the global base font size of the entire document.

The size Command Syntax

To modify the size of a specific section in a LibreOffice Math formula, enclose the target expression in curly braces {} immediately preceded by the size command and a size attribute:

size <value> { <expression> }

1. Absolute Font Size

You can specify a fixed point size (pt) directly by providing an absolute integer or decimal value:

• Syntax: size <number> { ... }
• Example: size 18 { x + y } = z
• Behavior: Sets the text within the brackets to exactly 18pt, regardless of the formula’s base font size setting.

2. Relative Increase and Decrease

To adjust the size relative to the currently active font size by adding or subtracting point sizes, use the plus (+) or minus (-) operators:

• Increase Syntax: size +<number> { ... }
  • Example: size +4 { A } + B (renders A 4 points larger than the default base size).
• Decrease Syntax: size -<number> { ... }
  • Example: x + size -3 { small text } (renders the enclosed text 3 points smaller than surrounding elements).

3. Proportional Scaling (Multiplication and Division)

You can scale the size of a section proportionally using multiplication (*) or division (/) factors:

• Multiplier Syntax: size *<factor> { ... }
  • Example: size *1.5 { E } = m c^2 (renders E at 150% of the surrounding font size).
  • Example: size *2 { \int } f(x)dx (doubles the standard size of the integral sign).
• Divisor Syntax: size /<factor> { ... }
  • Example: size /2 { \Delta } x (reduces the symbol to half its standard size).

Scope and Grouping Rules

• Single Elements: If applied to a single variable or standalone character without brackets, the attribute affects only that immediate character (e.g., size 20 x + y sizes only x).
• Grouped Expressions: Using grouping brackets { ... } applies the specified size attribute across multiple terms, operators, or nested equations (e.g., size *1.2 { a + b over c }).
• Nesting: Size attributes can be nested hierarchically. A relative change inside another sized block calculates its scale based on the parent block’s adjusted size rather than the global base size.