# Shape Mismatch in np.linalg.solve in soln-plugin-sampler (sampler.py) Causing ValueError
**URL:** https://pyfr.discourse.group/t/shape-mismatch-in-np-linalg-solve-in-soln-plugin-sampler-sampler-py-causing-valueerror/1152
**Category:** Bugs
**Tags:** plugins
**Created:** [24 August 2024 17:55 UTC](https://pyfr.discourse.group/t/shape-mismatch-in-np-linalg-solve-in-soln-plugin-sampler-sampler-py-causing-valueerror/1152 "2024-08-24T17:55:05Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Debdoot](https://pyfr.discourse.group/u/Debdoot)
#### Post date: [24 August 2024 17:55 UTC](https://pyfr.discourse.group/t/shape-mismatch-in-np-linalg-solve-in-soln-plugin-sampler-sampler-py-causing-valueerror/1152/1 "2024-08-24T17:55:05Z")
# Nature of bug
Error in using **[soln-plugin-sampler]** ( associated to sampler.py file)
# Error print out (if applicable)
```auto
ValueError: solve: Input operand 1 has a mismatch in its core
dimension 0, with gufunc signature (m,m), (m, n) ›(m,n) (size 20 is different from 2)
```
# PyFR information
- PyFR version: pyfr 2.0.2
- OS: NAME=CentOS Linux; VERSION=“7 (Core)”
- System description: Architecture x86\_64; Intel(R) Xeon(R) CPU E5-2640 v2 @ 2.00GHz ; NVIDIA v100
- Compiler and version: gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-16)
- Backend (if applicable): CUDA
# Git diff that reproduces bug
```auto
diff --git a/pyfr/plugins/sampler.py b/pyfr/plugins/sampler.py
index 818dc81..79dd8e3 100644
--- a/pyfr/plugins/sampler.py
+++ b/pyfr/plugins/sampler.py
@@ -43,7 +43,13 @@ def _plocs_to_tlocs(sbasis, spts, plocs, tlocs):
for k in range(3):
jac_ops = sbasis.jac_nodal_basis_at(ktlocs)
kjplocs = np.einsum('ijk,jkl->kli', jac_ops, spts)
- ktlocs -= np.linalg.solve(kjplocs, kplocs - plocs)
+ # ktlocs -= np.linalg.solve(kjplocs, kplocs - plocs)
+# Adjust the shape of kplocs - plocs to match kjplocs
+ rhs = (kplocs - plocs)[..., np.newaxis]
+
+# Solve the linear system
+ ktlocs -= np.linalg.solve(kjplocs, rhs).reshape(ktlocs.shape)
+
ops = sbasis.nodal_basis_at(ktlocs)
np.einsum('ij,jik->ik', ops, spts, out=kplocs)
```
---
### Author:  [@fdw](https://pyfr.discourse.group/u/fdw)
#### Post date: [24 August 2024 17:55 UTC](https://pyfr.discourse.group/t/shape-mismatch-in-np-linalg-solve-in-soln-plugin-sampler-sampler-py-causing-valueerror/1152/2 "2024-08-24T17:55:49Z")
Please provide an .ini file which reproduces the issue (ideally with a built-in test case).
Regards, Freddie.
---
### Author:  [@fdw](https://pyfr.discourse.group/u/fdw)
#### Post date: [29 August 2024 18:23 UTC](https://pyfr.discourse.group/t/shape-mismatch-in-np-linalg-solve-in-soln-plugin-sampler-sampler-py-causing-valueerror/1152/3 "2024-08-29T18:23:50Z")
As a follow up this appears to be an issue with NumPy v2. A simple workaround is to downgrade to 1.26. Alternatively, you can switch to the current development version of PyFR where this issue is resolved.
Regards, Freddie.
---
### Author:  [@Debdoot](https://pyfr.discourse.group/u/Debdoot)
#### Post date: [6 September 2024 01:22 UTC](https://pyfr.discourse.group/t/shape-mismatch-in-np-linalg-solve-in-soln-plugin-sampler-sampler-py-causing-valueerror/1152/4 "2024-09-06T01:22:06Z")
Thank you for the suggestions, Dr. Freddie.