TEND-BMAT(1)

💖 TEND-BMAT 💖

okay bestie, so this is tend-bmat, and it lives in the User Commands section of the manual. it's a little tool that does one job and does it iconically: it makes you a B-matrix out of your gradient directions. no cap.

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🌸 NAME 🌸

tend-bmat — calculate B-matrix given gradient directions ✨

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🎀 SYNOPSIS 🎀

tend bmat -i <grads> [-o <nout>]

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🦋 DESCRIPTION 🦋

okay so here's the vibe: this thing calculates the B-matrix from your gradient directions, and it does it assuming there's no diffusion weighting coming from the other imaging gradients. that's the whole deal, that's the assignment, and it ate. 💅

the input is a 3-by-N array of floats or doubles — each row is one of the gradient directions you used for diffusion-weighted imaging. like, one gradient per row, that's it.

and honestly? the easiest way to hand that over is a plain text file with one gradient per line, no punctuation. no commas, no brackets, no drama. just vibes and numbers. 🍓

now here's a thing you gotta know: the gradient vector coefficients are used as is, without normalization. lowkey important — it doesn't scale them for you, and that's on purpose, because sometimes you want different gradient strengths. so it respects your numbers exactly as you typed them. periodt. 👑

the output? one row of the B-matrix per line, with the coefficient ordering being:

Bxx, Bxy, Bxz, Byy, Byz, Bzz

and listen — the off-diagonal elements are NOT pre-multiplied by 2. not. pre-multiplied. by. two. so don't come for me later when you're doing math and it's off by a factor, bestie, because it told you. 😭

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✨ OPTIONS ✨

• -i <grads> — array of gradient directions 💜
• -o <nout> — output B matrix (string) — default: "-" 🫶

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👑 SEE ALSO 👑

tend(1), tend-estim(1), tend-msim(1), tend-sim(1)

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and that's the whole page, fr fr. this version is the April 2021 one, from the User Commands manual, and the page itself is TEND-BMAT(1). go forth and compute your B-matrix, main character. 🌈⭐🧚💖