The Indian Mathematician Who Measured Everest: Radhanath Sikdar
In 1852 Radhanath Sikdar, a mathematician with the Great Trigonometrical Survey, worked out that "Peak XV" was the highest mountain on Earth. The story…
Read article →Atul Vij
Monthly Totals From Daily Data in Excel (SUMIFS + EOMONTH, Pivot and GROUPBY)
Monthly Totals From Daily Data in Excel (SUMIFS + EOMONTH, Pivot and GROUPBY)
Turn a daily sales list into month-wise totals: SUMIFS with EOMONTH date bounds, a month-by-region grid, TEXT month keys, pivot grouping and the new…
Read article →Excel LAMBDA Lesson 8: Package and Share Your Function Library
Excel LAMBDA Lesson 8: Package and Share Your Function Library
Collect your LAMBDA functions in one library workbook, copy them to other files, use the Advanced Formula Environment and keep versions under control.
Read article →Excel LAMBDA Lesson 7: Optional Arguments and Error Handling
Excel LAMBDA Lesson 7: Optional Arguments and Error Handling
Make LAMBDA functions friendly: optional parameters with ISOMITTED, sensible defaults, SAFEDIV and clear messages for bad input.
Read article →Excel LAMBDA Lesson 6: MAP, BYROW, BYCOL and MAKEARRAY
Excel LAMBDA Lesson 6: MAP, BYROW, BYCOL and MAKEARRAY
Apply your functions across whole ranges: MAP for every cell, BYROW and BYCOL for row and column totals, MAKEARRAY to generate grids.
Read article →Excel LAMBDA Lesson 5: REDUCE and SCAN (Running Balances, Multi-Replace)
Excel LAMBDA Lesson 5: REDUCE and SCAN (Running Balances, Multi-Replace)
Use REDUCE to fold a list into one answer and SCAN to keep every step: running bank balances, compound growth and a MULTIREPLACE function.
Read article →Build Your Own LLM, Lesson 4: Embeddings and Your First Neural Language Model
Build Your Own LLM, Lesson 4: Embeddings and Your First Neural Language Model
Rebuild the bigram model as a neural network in PyTorch, train it with gradient descent, and add embeddings — the vectors that let language…
Read article →Rolling Totals in Excel: Last 7 Days, Last 30 Days and Moving Averages
Rolling Totals in Excel: Last 7 Days, Last 30 Days and Moving Averages
Sum or count the last 7 or 30 days with SUMIFS and TODAY(), build a 7-day moving average, a trailing-12-month total, and a rolling…
Read article →Excel LAMBDA Lesson 4: Financial-Year Date Functions
Excel LAMBDA Lesson 4: Financial-Year Date Functions
FYSTART, FYLABEL, FYQTR, DAYSLEFT and AGEYEARS as LAMBDA functions for the Indian April-March financial year.
Read article →Excel LAMBDA Lesson 3: Text Cleaning Functions
Excel LAMBDA Lesson 3: Text Cleaning Functions
CLEANNAME, INITIALS, DIGITSONLY, WORDCOUNT and MASK: custom LAMBDA functions for messy names, phone numbers and sensitive data.
Read article →Excel LAMBDA Lesson 2: GST, Lakhs and Money Functions
Excel LAMBDA Lesson 2: GST, Lakhs and Money Functions
Build GSTINCL, GSTEXCL, GSTONLY, CGST/SGST, LAKHS, CRORE and ROUNDTO5 as reusable LAMBDA functions for Indian invoices and reports.
Read article →Excel LAMBDA Lesson 1: Your First Custom Function
Excel LAMBDA Lesson 1: Your First Custom Function
What LAMBDA is, how to test it inline, save it in Name Manager and call it like a built-in function. With the difference between…
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