# How to extract component of a complex grid?
**URL:** https://forum.generic-mapping-tools.org/t/how-to-extract-component-of-a-complex-grid/6073
**Category:** GMT.jl Q&A
**Tags:** gmt
**Created:** [July 23, 2025, 9:18pm UTC](https://forum.generic-mapping-tools.org/t/how-to-extract-component-of-a-complex-grid/6073 "2025-07-23T21:18:43Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@TFJospin](https://forum.generic-mapping-tools.org/u/TFJospin)
#### Post date: [July 23, 2025, 9:18pm UTC](https://forum.generic-mapping-tools.org/t/how-to-extract-component-of-a-complex-grid/6073/1 "2025-07-23T21:18:44Z")
How To read or write the real component of a complex grid in GMT ?.
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### Author:  [@Joaquim](https://forum.generic-mapping-tools.org/u/Joaquim)
#### Post date: [July 23, 2025, 10:10pm UTC](https://forum.generic-mapping-tools.org/t/how-to-extract-component-of-a-complex-grid/6073/2 "2025-07-23T22:10:28Z")
Read and write are two rather different operations. What is it that you are trying to read? And what for?
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### Author:  [@TFJospin](https://forum.generic-mapping-tools.org/u/TFJospin)
#### Post date: [July 24, 2025, 8:23am UTC](https://forum.generic-mapping-tools.org/t/how-to-extract-component-of-a-complex-grid/6073/3 "2025-07-24T08:23:28Z")
I have applied an arcsinus function to a grid containing values greater than ±1. To avoid complex parts appearing in the result, I want the final grid to contain only real values.
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### Author:  [@Joaquim](https://forum.generic-mapping-tools.org/u/Joaquim)
#### Post date: [July 24, 2025, 10:26am UTC](https://forum.generic-mapping-tools.org/t/how-to-extract-component-of-a-complex-grid/6073/4 "2025-07-24T10:26:30Z")
Don’t know what GMT does in those circumstances but it won’t write an imaginary grid. The simplest way to solve your issue is to use `grdclip` to insure data is on a valid domain.