# NMath User's Guide

53.1 Exception Types (.NET, C#, CSharp, VB, Visual Basic, F#)

The following exception classes inherit from .

 Exception Description Thrown when MKL returns an error condition when computing an FFT. Thrown when an out of range index is passed to an NMath function. Thrown when an invalid argument is passed to an NMath function. Thrown when a histogram operation results in invalid bin boundaries. Thrown when NMath cannot load a kernel assembly. Thrown when a matrix operation requiring a square matrix is presented with a non-square one. Exception thrown when an operation is per­formed with operands whose sizes are incompatible with the operation; for example, if you try to add two vectors with different lengths, or take the inner product of matrices A and B when the number of columns of A is not equal to the number of rows of B. Thrown when a method encounters a faulty text representation; for example, if you try to create a vector from a string that has an invalid format. Thrown when a matrix operation requiring a non-singular matrix is presented with a singular one.

For example, this code attempts to multiply two matrices with different dimensions, and catches a MismatchedSizeException:

Code Example – C#

```DoubleComplexMatrix A =
```
```   new DoubleComplexMatrix( 3, 3, new DoubleComplex(1,0) );
```
```DoubleComplexMatrix B =
```
```   new DoubleComplexMatrix( 2, 2, new DoubleComplex(1,0) );

```

```DoubleComplexMatrix C;
```
```try
```
```{
```
```   C = A * B;
```
```}
```
```catch( MismatchedSizeException e )
```
```{
```
```   Console.WriteLine( "Oops - " + e.Message );
```
```}
```

Code Example – VB

```Dim A As New DoubleComplexMatrix(3, 3, New DoubleComplex(1, 0))
```
```Dim B As New DoubleComplexMatrix(2, 2, New DoubleComplex(1, 0))

```

```Dim C As DoubleComplexMatrix
```
```Try
```
```  C = A * B
```
```Catch E As MismatchedSizeException
```
```  Console.WriteLine("Oops - " & E.Message)
```
```End Try
```

Matrices must have the same dimensions to be combined using the element-wise operators.

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